OPTICAL IMAGES. 
lens, but on the same side of it with the object, as explained 
in (36). 
61. With the same lens the dispersion will increase with the 
refraction, and consequently the more the image is magnified 
the greater will be the dispersion and the aberration, and the more 
confused and indistinct the image. 
62. It might naturally therefore be supposed that if two lenses 
made of different transparent substances produce images of the 
same object at the same distance from them, and consequently 
equally magnified, they would produce the same dispersion and 
aberration. It is found, however, that this is not the case. A 
lens of diamond and a lens of glass may be so formed that the 
same object being placed at equal distances from them, the 
distances at which the violet image will be produced shall be 
exactly equal, but the same equality will not prevail between the 
distances of the red image and those of the intermediate colours. 
112 
