### Angle of Vision

"The angle under which the rays of light, coming from the extremities of an object, cross each other…

### Chromatic Aberration

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

### Eastern Crown

"EASTERN CROWN. A crown with rays proceeding from a circle, called by heralds an Eastern crown, is found…

### Divider with Leaves and Sun Rays

This divider has leaves and small round kernels featured in a design on the sides. The center area has…

### Illumination of a Surface When the Surface is not Perpendicular to the Source

Illustration modeling the illumination on a surface when the surface is not perpendicular to hte rays…

### Converging Rays and a Double Convex Lens

"Thus the pencils of converging rays, are rendered still more convergent by their passage through the…

### Diverging Rays from a Double Convex Lens

"If diverging rays fall on the surface of the same lens, they will, by refraction, be rendered less…

### Rays of Light

"Rays of light are said to diverge, when they proceed from the same point, and constantly recede from…

### Focus of a Concave Mirror

"The focus of a concave mirror is the point where the rays are brought together by reflection." -Comstock…

### Convergent Rays in a Concave Mirror

"Thus, were the rays falling on the mirror parallel, the focus would be at a' but in consequence of…

### Divergent Rays in a Concave Mirror

"...be made obvious...where the diverging rays 1, 2, 3, 4 form a focus at the point o, whereas, had…

### Rays Diverging from Beyond the Center of Curvature on a Concave Mirror

"When the rays diverge form a point at a distance from the mirror less than that of the principal focus,…

### Concave Mirror with Image and Focus

"The focus of each point chose may be determined by tracing two rays from the point, and locating their…

### Object Within the Focus in a Concave Mirror

"...let us suppose the object a, to be placed before the mirror, and nearer to it than the principal…

### Convex Mirror

"Let us suppose that a, is a luminous point, from which a pencil of diverging rays falls upon a convex…

### Plane Inclined Mirrors

"The incident rays, a and b, being parallel before they reach the reflectors, are thrown off at unequal…

### Prism Spectroscope from the Late 19th Century

"...a tube with a slit at the further end through which the light enters, and at the other end a collimating…

An instrument which serves to transform radiant energy into mechanical work. Have 4 vanes, with one…

### Ray Pointing Down

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration…

### Ray Pointing Down and Left

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration…

### Ray Pointing Down and Right

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration…

### Ray Pointing Left

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration…

### Ray Pointing Right

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration…

### Ray Pointing Up

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration…

### Ray Pointing Up and Right

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration…

### Ray Pointing Up and Right

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration…

### Pencils of Rays

"These pencils of rays not only flow from the points designated in the figure, but in the same manner…

### Divergent Rays

"From the surface of a plane mirror, parallel rays are reflected parallel; but the convex mirror causes…

### Reflected Light

"The apparatus shown is used to prove that incident rays and reflected rays are equal." -Avery 1895

### Explanation of Reflection

"Consider a beam of light as made up of a number of ehter waves moving forward in air and side by side,…

### Parabolic, Reflector

A polished surface of metal, or any other suitable material, applied for the purpose of reflecting rays…

### Explanation of Refraction

"Thus, when erher waves that constitute light are transmitted through glass, they are hindered by the…

### Rose-en-Soleil

"The rose argent of the House of York, surrounded with rays, as of the sun."—Aveling, 1891

### Definitions, Segment, Ray, Line

Illustrations of a segment, a ray, and a line that can be used when providing definitions.

### Placoid Scales of a Shark

These placoid scales are found in cartilaginous fishes. They are also called dermal denticles. These…

### Skate

"Skate is the popular name for any individual of a section of the genus Raia, differing from the rays…

### Direct Vision Spectroscope

"...an instrument which gives a spectrum when the source of the light is in a straight line with the…

### One Spine on the Ventral Fin of a Bony Fish

"A fin-spine; one of the unjointed and unbranched sharp bony rays of the fins, such as those the presence…

### Ten Spines on the Fins of a Bony Fish

"A fin-spine; one of the unjointed and unbranched sharp bony rays of the fins, such as those the presence…

### Three Spines on the Anal Fin of a Bony Fish

"A fin-spine; one of the unjointed and unbranched sharp bony rays of the fins, such as those the presence…

### Greek Square Panel

The Greek square panel is found on the coffer of the Propylaea ceiling, the entrance to the Acropolis…

### Refracting Telescope

"Suppose a, to be a distinct object, from which pencils of rays flow from every point toward the object…

### Torpedo

Torpedo is a group of rays, commonly called electric rays or torpedoes. It is the only genus in the…