23S optics. 



as the candle is nearer to, or farther from, its 

 focus j and where the rays meet, 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, ABC (Fig. 7.) be placed 

 beyond the focus F of the convex glass, d e f, 

 some of the rays which flow from every point of 

 the object, on the side next the glass, will fall 

 upon it, and after passing through it, they will be 

 converged into as many points on the opposite 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 A d, A e, Af, flowing from the point A, will 

 converge in the space d a J\ and by meeting at a, 

 will there form the image of the point A. The 

 rays B d, B e, B f, flowing from the point B, will 

 be united at b, by the refraction of the glass, and 

 will there form the image of the point B. And 

 the rays C d, C e, C f, flowing from the point C, 

 will be united at c, where they will form the image 

 of the point C. And so of ail the intermediate 

 points between A and C. 



If the object A B C be brought nearer to the 

 glass, the picture a b c 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 cannot be so soon collected 

 into the corresponding points behind it. Conse- 

 quently, if the distance of the object ABC (Fig. S.) 

 be equal to the distance e B of the focus of the 

 glass, the rays of each pencil will be so refracted 

 by passing through the glass, that they will go out 

 of it parallel to each other: as d I, e H, fh, from 

 the point C; d G, e K, j^D, from the point B; 



14 



