"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…

"The spherical aberration of a concave mirror is the deviation of some of the reflected light from the focus, as shown It arises from the curvature of the mirror, and causes an indistinctness or blurring of the image." -Avery 1895

Spherical Aberration of a Concave Mirror

"The spherical aberration of a concave mirror is the deviation of some of the reflected light from the…

"When radiant energy passes through a medium bounded by parallel planes, the refractions at the two surfaces are equal and contrary in direction. The direction after passing through the plate is parallel to the direction before entereing the plate; the rays merely suffer lateral aberration." -Avery 1895

Refraction by Plates

"When radiant energy passes through a medium bounded by parallel planes, the refractions at the two…