Lens n. (pl. lenses) (Opt.) A piece of glass, or other transparent substance, ground with two opposite regular surfaces, either both curved, or one curved and the other plane, and commonly used, either singly or combined, in optical instruments, for changing the direction of rays of light, and thus magnifying objects, or otherwise modifying vision. In practice, the curved surfaces are usually spherical, though rarely cylindrical, or of some other figure. Lenses Note: Of spherical lenses, there are six varieties, as shown in section in the figures herewith given: viz., a plano-concave; b double-concave; c plano-convex; d double-convex; e converging concavo-convex, or converging meniscus; f diverging concavo-convex, or diverging meniscus.
Crossed lens (Opt.), a double-convex lens with one radius equal to six times the other.
Fresnel lens (Opt.), a compound lens formed by placing around a central convex lens rings of glass so curved as to have the same focus; used, especially in lighthouses, for concentrating light in a particular direction; so called from the inventor.
Multiplying lens or Multiplying glass (Opt.), a lens one side of which is plane and the other convex, but made up of a number of plane faces inclined to one another, each of which presents a separate image of the object viewed through it, so that the object is, as it were, multiplied.
... in her two hands so that the lens looked at the wheels, gazed wistfully after them as they rose and went humming away toward the rising sun, that had just cleared the jagged rim of mountains and was gilding the ledge behind her. They climbed and swerved a little to the ... — Skyrider • B. M. Bower Read full book for free!
... loitering about, without visible aim, they class him as a mild imbecile, and let him go; but boys are nature's detectives, and one does not so easily evade their scrutinizing eyes. I know full well that, while I study their ways, they are noting mine through a clearer lens, and are probably taking my measure far better than I take theirs. One instinctively shrinks from making a sketch or memorandum while they are by; and if caught in the act, one fondly hopes to pass for some harmless speculator in real estate, ... — Oldport Days • Thomas Wentworth Higginson Read full book for free!
... lot of nonsense talked about motherhood softening women. It may soften them in some ways, but there are many others in which it hardens them. It draws their power of love together into a fixed point, just as the lens of a burning-glass concentrates the vague warmth of the sun into one small and fiercely illuminated area. It is a form of selfishness, I suppose, but it is a selfishness nature imposes upon us. And it is sanctified by the end it serves. At every turn, ... — The Prairie Child • Arthur Stringer Read full book for free!
... with a lens the Etruscan jewels of our own collection, I discerned in the zones of the tiny grains (which are characteristic of the work of these patient artists) certain defects, such as those which are made in enamel by the melting of the gold. These observations ... — The Atlantic Monthly, Volume 18, No. 108, October, 1866 • Various Read full book for free!
... of physical science cannot reveal the why and the wherefore, let us, for a brief moment, disclose some of the wonders that declare their existence, when subjected to the penetrating alchemical lens, of the inward spirit. The first thing that intrudes itself upon our notice, by virtue of its primary importance, is the grand fact of biogenesis—life emanating from life. We perceive every external form to be the physical symbol of a corresponding degree of spiritual life; that ... — The Light of Egypt, Volume II • Henry O. Wagner/Belle M. Wagner/Thomas H. Burgoyne Read full book for free!
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