Illustration of an ellipse, whose major axis is vertical, inscribed in a circle whose diameter is equal to the length of the major axis of the ellipse. The ellipse is externally tangent to the circle.

Ellipse Inscribed In A Circle

Illustration of an ellipse, whose major axis is vertical, inscribed in a circle whose diameter is equal…

Illustration of 16 concentric congruent ellipses that are rotated about the center at equal intervals of 22.5°. The ellipses are externally tangent to the circle in which they are inscribed.

16 Rotated Concentric Ellipses

Illustration of 16 concentric congruent ellipses that are rotated about the center at equal intervals…

Illustration of 2 concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter is equal to the length of the major axes of the ellipses. The ellipses, which decrease in width in equal increments, are externally tangent to the circle. The illustration could be used as a 3-dimensional drawing of a sphere.

2 Ellipses Inscribed In A Circle

Illustration of 2 concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter…

Illustration of 2 concentric congruent ellipses that are rotated about the center at 90°. The ellipses are externally tangent to the circle in which they are inscribed.

2 Rotated Concentric Ellipses

Illustration of 2 concentric congruent ellipses that are rotated about the center at 90°. The ellipses…

Illustration of 4 concentric congruent ellipses that are rotated about the center at equal intervals of 45°. The ellipses are externally tangent to the circle in which they are inscribed.

4 Rotated Concentric Ellipses

Illustration of 4 concentric congruent ellipses that are rotated about the center at equal intervals…

Illustration of 8 concentric congruent ellipses that are rotated about the center at equal intervals of 22.5°. The ellipses are externally tangent to the circle in which they are inscribed.

8 Rotated Concentric Ellipses

Illustration of 8 concentric congruent ellipses that are rotated about the center at equal intervals…

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter is equal to the length of the major axes of the ellipses. The ellipses, which decrease in width in equal increments until the smallest one is a line, are externally tangent to the circle. The illustration could be described as a circle rotated about the poles of the vertical axis. It could also be used as a 3-dimensional drawing of a sphere.

Ellipses Inscribed In A Circle

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter…

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter is equal to the length of the major axes of the ellipses. The ellipses, which decrease in width in equal increments until the smallest one is a line, are externally tangent to the circle. The illustration could be described as a circle rotated about the poles of the vertical axis. It could also be used as a 3-dimensional drawing of a sphere.

Ellipses Inscribed In A Circle

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter…

"A concave mirror reflects from a curved surface hollowing in like he inside of an orange." —Quackenbos 1859

Concave Mirror

"A concave mirror reflects from a curved surface hollowing in like he inside of an orange." —Quackenbos…

"When the rays diverge form a point at a distance from the mirror less than that of the principal focus, the reflected rays diverge as if from a point back of the mirrir. This point, b, is a virtual focus." -Avery 1895

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,…

"A convex mirror reflects from a curved surface rounding out like the outside of an orange." —Quackenbos 1859

Convex Mirror

"A convex mirror reflects from a curved surface rounding out like the outside of an orange." —Quackenbos…

"Parallel rays strike the convex mirror, reflect, and diverge as if they had originated from a virtual focus inside the mirror. Focus F is located between the surface of the mirror and the mirror's center if it were a full body sphere." —Quackenbos 1859

Reflection by Convex Mirrors

"Parallel rays strike the convex mirror, reflect, and diverge as if they had originated from a virtual…

"Suppose the arrow a to be the object reflected b the mirror d c; the incident rays a, flowing from the end of the arror being thrown back by reflection, will meet the eye in the same state of dicergence that they would do, if they proceded to the same distance behind the mirrr, that the eye is before it, as at o." -Comstock 1850

Plane Mirror

"Suppose the arrow a to be the object reflected b the mirror d c; the incident rays a, flowing from…

"A plane mirror reflects from a flat surface, like a common looking glass." —Quackenbos 1859

Plane Mirror

"A plane mirror reflects from a flat surface, like a common looking glass." —Quackenbos 1859

"A prism is a piece of glass, having for its sides three plane surfaces and for its ends two equal and parallel triangles." —Quackenbos 1859

Prism

"A prism is a piece of glass, having for its sides three plane surfaces and for its ends two equal and…

"Consider a beam of light as made up of a number of ehter waves moving forward in air and side by side, as represented by the rays A, B, C. Imagine a plane, MN, normal to these yars, attached to the waves and moving forward in a straight line. As the wave front advances beyond MN, the ray, A, strikes the reflecting surface, RS, and is turned back into the air in accordance with the law just given." -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,…

"Let a ray pass towards a mirror in the line a, c, it will be reflected off in the direction of c, d, making the angles 1 and 2 exactly equal." -Comstock 1850

Reflecion of Light

"Let a ray pass towards a mirror in the line a, c, it will be reflected off in the direction of c, d,…

"Reflection of light from a smooth surface." —Croft 1917

Reflection of Light from a Smooth Surface

"Reflection of light from a smooth surface." —Croft 1917

A polished surface of metal, or any other suitable material, applied for the purpose of reflecting rays of light, heat, or sound in any required direction.

Parabolic, Reflector

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

"...represents two parabolic reflectors, mn and op. It is a peculiarity of such reflectors that rays starting from the focus, as F will be reflected as parallel rays, and that parallel rays falling upon sucha reflector will converge at the focus, as F'. Hence, two such reflectors may be placed in such a sposition that sound waves starting from one focus shall, after two reflections, be converged at the other focus...Two reflectors so placed are said to be conjugate to each other." -Avery 1895

Parabolic Reflectors

"...represents two parabolic reflectors, mn and op. It is a peculiarity of such reflectors that rays…

"The reflecting telescope has an objective a concave mirror, tecnically called a speculum. The images formed by the speculum are brought to the eyepiece in several different ways. Sometimes the eyepiece consists of a series of convex lenses placed in a horizontal tube." — Avery, 1895

Reflecting telescope

"The reflecting telescope has an objective a concave mirror, tecnically called a speculum. The images…