its not being so, however, causes the imaga to be formed nearer its proper position ; thus a certain want of flatness of field is generally an advantage, instead of otherwise. We now come to one of the most beautiful things connected with the construction of a lens, viz., its achromatism. A ray of… … similar prism to be added, as shown by the upper dotted prism, we should have another refraction and dispersion, but in opposite directions to those due to the first prism, so that the coloured rays would join together again and form a white one, which would pro- ceed in its original direction just…
Photography
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
