"Because of their greater refrangibility, the focus of the violet rays is nearer the lens than the focus of the red rays, as illustrated. If the screen is as near the lens as the focus marked v, the outer fringe is red. If the screen is as far from the lens as the focus marked r, the outer fringe is violet. This difference in the deviation of differently colored rays is called chormatic aberration." -Avery 1895

Chromatic Aberration

"Because of their greater refrangibility, the focus of the violet rays is nearer the lens than the focus…