"Ambulacra of Star-fish, As seen in a longitudinal and vertical section of one of the rays; and three of them in a separate figure on a larger scale, in which they are shown in different conditions; a, a, a, tubular feet; b, b, b, internal vesicles; c, the organ which supplies the fluid with which they are filled." — Chambers' Encyclopedia, 1875

Ambulacra

"Ambulacra of Star-fish, As seen in a longitudinal and vertical section of one of the rays; and three…

"Notwithstanding its name is is a hideous-looking creature, with two enormous pectoral fins, said to have given it its name, from a fancied resemblence to the wings of angels." — Goodrich, 1859

Angelfish

"Notwithstanding its name is is a hideous-looking creature, with two enormous pectoral fins, said to…

"The rays are sometimes very short, or altogether wanting, the body having the form of a pentagonal disk." — Encyclopedia Britannica, 1893

Astrogonium Phrygianum

"The rays are sometimes very short, or altogether wanting, the body having the form of a pentagonal…

Decorative letter 'b', with a sun and polearm behind it.

B

Decorative letter 'b', with a sun and polearm behind it.

This illustration shows the cross-section of a stem of Botrychium: p, pith; x, xylem; m, ray; c, cambium; ph, phloem; e, endodermis; cr, cortex.

Botrychium

This illustration shows the cross-section of a stem of Botrychium: p, pith; x, xylem; m, ray; c, cambium;…

"Catadioptric Holophote.—Part of the anterior hemisphere of rays is intercepted and at once parallelized by the lens L, whose principal focus (i.e., for parallel rays) is in the center of the flame, while the remainder is intercepted and made parallel by the paraboloid a, and thus the double agents in Fresnel's design are dispensed with. The rays of the posterior hemisphere are reflected by the spherical mirror b back again through the foxus, whence passing onwards one portion of them falls on the lens and the rest on the paraboloid, so as finally to emerge in union with and parallel to the front rays." —The Encyclopedia Britannica, 1910

Catadioptric Holophote

"Catadioptric Holophote.—Part of the anterior hemisphere of rays is intercepted and at once parallelized…

"Catadioptric Holophote.—Part of the anterior hemisphere of rays is intercepted and at once parallelized by the lens L, whose principal focus (i.e., for parallel rays) is in the center of the flame, while the remainder is intercepted and made parallel by the paraboloid a, and thus the double agents in Fresnel's design are dispensed with. The rays of the posterior hemisphere are reflected by the spherical mirror b back again through the foxus, whence passing onwards one portion of them falls on the lens and the rest on the paraboloid, so as finally to emerge in union with and parallel to the front rays." —The Encyclopedia Britannica, 1910

Catadioptric Holophote

"Catadioptric Holophote.—Part of the anterior hemisphere of rays is intercepted and at once parallelized…

"Condensing Apparatus for Steamer's Side Lights.—By means of this application of the condensing principle all the light can be distributed with strict equality over 112 degrees, which is the arc prescribed for steamers by the Board of Trade. Several of the Transatlantic and other steamers have adopted this kind of apparatus, which is hung on gimbals and placed in iron towers, having an entry from below the deck, which can be made use of in bad weather." —The Encyclopedia Britannica, 1910

Condensing Apparatus

"Condensing Apparatus for Steamer's Side Lights.—By means of this application of the condensing…

"Condensing Apparatus for Steamer's Side Lights.—By means of this application of the condensing principle all the light can be distributed with strict equality over 112 degrees, which is the arc prescribed for steamers by the Board of Trade. Several of the Transatlantic and other steamers have adopted this kind of apparatus, which is hung on gimbals and placed in iron towers, having an entry from below the deck, which can be made use of in bad weather." —The Encyclopedia Britannica, 1910

Condensing Apparatus

"Condensing Apparatus for Steamer's Side Lights.—By means of this application of the condensing…

"Fixed Conensing Light for a Single Sector, 1850.—The holophote Light pLp throws its whole light on straight condensing prisms c, each of which distributes the rays over the required sector." —The Encyclopedia Britannica, 1910

Condensing Light

"Fixed Conensing Light for a Single Sector, 1850.—The holophote Light pLp throws its whole light…

"Condensing Octant.—The central fixed apparatus bb with spherical mirror dd throws its rays directly over the angle of 45 degrees pgp, while the supplemental rays fall upon the straight condensing prisms p, each of which spreads the incident rays parallel to the corresponding rays in the central angle pgp. In this way the whole of the front hemisphere of rays is parallelized in the vertical plane and spread equally over the 45 degree in azimuth." —The Encyclopedia Britannica, 1910

Condensing Octant

"Condensing Octant.—The central fixed apparatus bb with spherical mirror dd throws its rays directly…

"Condensing Octant.—The central fixed apparatus bb with spherical mirror dd throws its rays directly over the angle of 45 degrees pgp, while the supplemental rays fall upon the straight condensing prisms p, each of which spreads the incident rays parallel to the corresponding rays in the central angle pgp. In this way the whole of the front hemisphere of rays is parallelized in the vertical plane and spread equally over the 45 degree in azimuth." —The Encyclopedia Britannica, 1910

Condensing Octant

"Condensing Octant.—The central fixed apparatus bb with spherical mirror dd throws its rays directly…

"Condensing Quadrant.—The fixed apparatus bbb, with spherical mirror behind, throws its rays directly through the angle of 90 degrees afa', while the supplementary rays falling on the straight condensing prisms p, p, p', p' are sent out parallel to the corresponding rays in the unobstructed central quadrant of the main apparatus. The whole light will therefore be condensed equally over 90 degrees." —The Encyclopedia Britannica, 1910

Condensing Quadrant

"Condensing Quadrant.—The fixed apparatus bbb, with spherical mirror behind, throws its rays directly…

"The refraction of water is beautifully proved by the following simple experiment. Place an empty cup, with a shilling on the bottom, in such a position that the side of the cup will just hide the piece of money from the eye. Then let another person fill the cup with water, keeping the eye in the same position as before. As the water is poured in, the shilling will be come visible, appearing to rise with the water. The effect of the water is to bend the ray of light coming from the shilling, so as to make it meet the eye below the point where it otherwise would. Thus the eye could not see the shilling in the direction of c, since the line, of vision is towards a, and c is hidden by the side of the cup. But the refraction of the water bends the way downwards, producing the same effect as though the object had been raised upwards, and hence it becomes visible." —Comstock, 1850

Cup and Shilling

"The refraction of water is beautifully proved by the following simple experiment. Place an empty cup,…

Draftsman's fourth method for drawing an ellipse, case 1

Ellipse Fourth Method Case 1

Draftsman's fourth method for drawing an ellipse, case 1

Draftsman's fourth method for drawing an ellipse, case 2

Ellipse Fourth Method Case 2

Draftsman's fourth method for drawing an ellipse, case 2

Draftsman's fourth method for drawing an ellipse, case 3

Ellipse Fourth Method Case 3

Draftsman's fourth method for drawing an ellipse, case 3

A light fixture or luminaire is an electrical device used to create artificial light.

Lighting Fixture

A light fixture or luminaire is an electrical device used to create artificial light.

A flashcard featuring an illustration of a Ray

Flashcard of a Ray

A flashcard featuring an illustration of a Ray

"Holophotal Catadioptric Apparatus Revolving round a Central Flame." —The Encyclopedia Britannica, 1910

Holophotal Catadioptric

"Holophotal Catadioptric Apparatus Revolving round a Central Flame." —The Encyclopedia Britannica,…

"Noted for the smoothness of its skin; sometimes called <em>Ray-mouthed Dog</em>; takes bait, but is less rapacious than other species; common on the British coasts." &mdash; Goodrich, 1859

Smooth Hound

"Noted for the smoothness of its skin; sometimes called Ray-mouthed Dog; takes bait, but is…

Draftsman's second method for drawing a hyperbola

Hyperbola Second Method

Draftsman's second method for drawing a hyperbola

Illustration modeling the illumination on a surface when the surface is not perpendicular to hte rays of light from a source of light.

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…

"If the object a be placed obliquely before the convex mirror, then the converging rays from its two extremities falling obliquely on its surface, would they prolonged through the mirror, meet at the point c, behind it. But instead of being thus continued, they are thrown back by the mirror in less convergent lines, which meet the eye at e, it being, as we have seen, one of the properties of this mirror, to reflect converging rays less convergent than before." -Comstock 1850

Curved Image

"If the object a be placed obliquely before the convex mirror, then the converging rays from its two…

"Section of <em>Ampioxus</em>, fr, fin ray; ct, connective tissue; nc, notochord, ; snc, supraneural crest"&mdash;Finley, 1917

Section of a lancelet

"Section of Ampioxus, fr, fin ray; ct, connective tissue; nc, notochord, ; snc, supraneural…

"...let LN represent a glass biconvex lens, with centres of curvature at C and C', and AB, the incident ray." -Avery 1895

Refraction of Light through Bi Convex Lens

"...let LN represent a glass biconvex lens, with centres of curvature at C and C', and AB, the incident…

"Rays of light are said to diverge, when they proceed from the same point, and constantly recede from each other, as from the same point a. Rays of light are said to converge, when they approach each other in such a drection as finaly to meet at a point, as at b." -Comstock 1850

Rays of Light

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

"Parallel rays of light strike the concave mirror. The rays converge at the focus, F, which is halfway between the mirror surface and the center of the sphere that the mirror would form if it were a full sphere." &mdash;Quackenbos 1859

Reflection from Concave Mirrors

"Parallel rays of light strike the concave mirror. The rays converge at the focus, F, which is halfway…

"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." &mdash;Quackenbos 1859

Reflection by Convex Mirrors

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

"This will be understood [here] where the ray of light A B, proceeding from the eye, falls perpendicularly on the plane mirror B D. will be reflected back in the same line; but the ray C D coming from the feet, which falls obliquely on the mirror, will be reflected back under the same angle in the line D A; and since we see objects in the direction of the reflected rays, and the image appears at the same distance behind the mirror that is object is before it, we must continue the line A D to the feet, E, and for the same reason, the rays A B, from the eye, must be prolonged to F, as far behind the mirror as the line E extends, where the whole image will be represented." -Comstock 1850

Mirror Half the Length of the Object

"This will be understood [here] where the ray of light A B, proceeding from the eye, falls perpendicularly…

"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…

"When the Moon falls into the shadow of the Earth, the rays of the Sun are intercepted, or hid from her, and she then becomes eclipsed. when the Earth's shadow covers a part of her face, as seen by us, she suffers only a partial eclipse, one part of her disc being obscured, while the other part reflects the Sun's light. But when her whole surface is obscured by the Earth's shadow, she then suffers a total eclipse, and of a duration proportionate to the distance she passes through the Earth's shadow." &mdash;Comstock, 1850

Moon Eclipse

"When the Moon falls into the shadow of the Earth, the rays of the Sun are intercepted, or hid from…

Draftsman's second method for drawing a parabola

Parabola Second Method

Draftsman's second method for drawing a parabola

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

Prism

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

A genus of cartilaginous fishes. They are generally divided into numerous families, including the saw-fishes, electric rays, skates, sting-rays, and the eagle rays.

Ray

A genus of cartilaginous fishes. They are generally divided into numerous families, including the saw-fishes,…

"Azure, a ray of the sun issuing out of the dexter corner of the escutcheon. The lines on each side are not noticed. RAY. A stream of light proceeding from a luminous body." -Hall, 1862

Ray of Sun

"Azure, a ray of the sun issuing out of the dexter corner of the escutcheon. The lines on each side…

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

Ray Pointing Down

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

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration points down and toward the left.

Ray Pointing Down and Left

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

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration points down and toward the right.

Ray Pointing Down and Right

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

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

Ray Pointing Left

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

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

Ray Pointing Right

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

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

Ray Pointing Up

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

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration points up and toward the right.

Ray Pointing Up and Right

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

A ray has one endpoint and extends indefinitely in the other direction. The ray in this illustration points up and toward the left.

Ray Pointing Up and Right

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

"Is two to three feet long, including the tail. The flesh is tolerably food, common on European coasts" &mdash; Goodrich, 1859

Bordered Ray

"Is two to three feet long, including the tail. The flesh is tolerably food, common on European coasts"…

"It is remarkable for an electric battery situated between the pectorals and head and gills; this is indicated by two elevations extending along the back, and consists of numerous cells formed like honeycomb, this being, as is the similar provision of the <em>Gymnotus</em> or electric eel, amply supplied with nerves. On being touched the animal imparts a severe electric shock, sufficient to stun its prey." &mdash; Goodrich, 1859

Electric Ray

"It is remarkable for an electric battery situated between the pectorals and head and gills; this is…

The Starry Ray is so called for having a number of spines on its upper surface rising from rayed or star like bases; it reaches a length of 30 inches.

Starry Ray

The Starry Ray is so called for having a number of spines on its upper surface rising from rayed or…

"Its tail is arme with a sharp spine fives inches long, serated on both edges, with which it lacerates its enemies." &mdash; Goodrich, 1859

Sting Ray

"Its tail is arme with a sharp spine fives inches long, serated on both edges, with which it lacerates…

"Summer and Winter rays.&mdash;Let us suppose that the rays falling perpendicularly on a given extent of surface, impart to it a certain degree of heat, then it is obvious, that if the same number of rays be spread over twice that extent of surface, their heating power would be diminished in proportion, and that only half of the heat would be imparted. This is the effect produced by the Sun's rays in the Winter. They fall so obliquely on the Earth, as to occupy nearly double the space that the same number of rays do in the Summer." &mdash;Comstock, 1850

Rays

"Summer and Winter rays.—Let us suppose that the rays falling perpendicularly on a given extent…

"From the surface of a plane mirror, parallel rays are reflected parallel; but the convex mirror causes parallel rays falling on its surface to diverge, by reflection." -Comstock 1850

Divergent Rays

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

"Here, of the rays S A, S B, and S C, only the ray S C meets the eye of the spectator D. The spot C, therefore, will appear luminous to the spectator D, but no other spot of the water A B C." &mdash;Wells, 1857

Reflection

"Here, of the rays S A, S B, and S C, only the ray S C meets the eye of the spectator D. The spot C,…

"Mirror A/B is only half of person C's height. C is able to view his entire body through such a small mirror due to the angle of incidence from D to B to F." &mdash;Quackenbos 1859

Angle of Incidence and Reflection

"Mirror A/B is only half of person C's height. C is able to view his entire body through such a small…

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…

"Since air is a rarer medium and water is denser, as ray A passes into the water, it is refracted to C. Also note that as ray B leaves the water, it is refracted to D as it enters the air." &mdash;Quackenbos 1859

Refraction Between Mediums

"Since air is a rarer medium and water is denser, as ray A passes into the water, it is refracted to…

"Although a ray of light will pass in a straight line, when not interrupted, yet when it passes obliquely from one transparent body into another, of a different density, it leaves its linear direction, and is bent, or refracted more or less, out of its former course." -Comstock 1850

Refraction of Light

"Although a ray of light will pass in a straight line, when not interrupted, yet when it passes obliquely…

"Let a represent a, b water, and c a piece of glass. The ray d, striking each medium in a perpendicular direction." -Comstock 1850

Refraction, air, water, glass

"Let a represent a, b water, and c a piece of glass. The ray d, striking each medium in a perpendicular…

"If the ray passes in the opposite direction, i.e., from water into air, the process is the reverse of that just indicated. Let KA represent the incident ray." -Avery 1895

Refraction of Light Between Water and Air

"If the ray passes in the opposite direction, i.e., from water into air, the process is the reverse…

"If the coin were to be observed in an empty pan and then watched as the pan was filled with water, the image of the coin would be refracted to position N." &mdash;Quackenbos 1859

Refraction as seen by the Human Eye

"If the coin were to be observed in an empty pan and then watched as the pan was filled with water,…

"Diagram illustrating the points at which incident rays meet the retina. xx, optic axis; k, first nodal point; k', second nodal point; b, point where the image of B would be formed, were the eye properly accommodated for it; a, the retinal point where the image of A would be formed." &mdash;Martin, 1917

Retina

"Diagram illustrating the points at which incident rays meet the retina. xx, optic axis; k, first nodal…

Fishes are sometimes classed, in accordance with the structure of their scale, into Ctenoid, Ganoid, Cycloid, and Placoid. This illustration is Placoid scale of Ray.

Placoid Scale of Ray

Fishes are sometimes classed, in accordance with the structure of their scale, into Ctenoid, Ganoid,…