ISBN: 9781130331141

RareBooksClub. Paperback. New. This item is printed on demand. Paperback. 94 pages. Dimensions: 9.7in. x 7.4in. x 0.2in.This historic book may have numerous typos and missing text. Purc… Plus…

RareBooksClub. Paperback. New. This item is printed on demand. Paperback. 94 pages. Dimensions: 9.7in. x 7.4in. x 0.2in.This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1884 Excerpt: . . . They are called the ordinary rays. Those which form the extraordinary image (called the extraordinary rays) do not follow the law of sines, except when the refracting surface is parallel to the axis, and the plane of incidence perpendicular to the axis; and in this case their index of refraction (called the extraordinary index) is different from that of the ordinary rays. The ordinary index is 165, and the extraordinary l-48. When the plane of incidence is parallel to the axis, the extraordinary ray always lies in this plane, whatever be the direction of the refracting surface; but the ratio of the sines of the angles of incidence and refraction is variable. When the plane of incidence is oblique to the axis, the extraordinary ray generally lies in a different plane. We shall recur to the subject of double refraction in the concluding chapter of this volume. CHAPTER LXX. LENSES. 1000. Forms of Lenses. --A lens is usually a piece of glass bounded by two surfaces which are portions of spheres. There are two principal classes of lenses. 1. Converging lenses or convex lenses, which have one or other of the three forms represented in Fig. 714. The first of these is called double convex, the second plano-convex, and the third concavoconvex. This last is also called a converging meniscus. All three are thicker in the middle than at the edges. They are called converging, because rays are always more convergent or less divergent after passing through them than before. 2. Diverging lenses or concave lenses (Fig. 715) produce the opposite effect, and are characterized by being thinner in the middle than at the edges. Of the three forms represented, the first is double concave, the second plano-concave, and the third convexo-concave (also called a diverging meniscus). . . . This item ships from La Vergne,TN., RareBooksClub<

ISBN: 9781130331141

Augustin Privat-Deschanel, Paperback, English-language edition, Pub by General Books LLC Books, History~~General, Elementary-Treatise-On-Natural-Philosphy~~Augustin-Privat-Deschanel, 9999… Plus…

Augustin Privat-Deschanel, Paperback, English-language edition, Pub by General Books LLC Books, History~~General, Elementary-Treatise-On-Natural-Philosphy~~Augustin-Privat-Deschanel, 999999999, Elementary Treatise on Natural Philosphy, Augustin Privat-Deschanel, 1130331148, General Books LLC, , , , , General Books LLC<