. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. nicol's prism. 131 the refracting surfaces are perfect, and that no light is lost by absorption in the media. It is a curious fact, resulting from the polarizing poAver of a pile of glass plates, that the pile is more transparent when held at an obliquity greater than the angle of polarization than it is at that angle; and that the transparency in- creases with the obliquity. This is owing to the fact that the light which has been polarized
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. nicol's prism. 131 the refracting surfaces are perfect, and that no light is lost by absorption in the media. It is a curious fact, resulting from the polarizing poAver of a pile of glass plates, that the pile is more transparent when held at an obliquity greater than the angle of polarization than it is at that angle; and that the transparency in- creases with the obliquity. This is owing to the fact that the light which has been polarized by the first few laminae undergoes very little loss by reilcction on increasing the obliquity; but the amount i^olarizcd in those first refractions increases as the obliquity increases, more rapidly than the loss by reflection of the natural light falling on the same surfaces is increased. The intensity of the transmitted beam, therefore, becomes actually greater as the obliquity is greater: a fact which is the reverse of what happens with a single plate. A remarkable fact in regard to the condition of lig-ht emitted at great obli- quities from luminous solids or liquids, was discovered by Mr. Arago. When- ever the light of an incandescent body of either of these classes is examined as it proceeds directly from the body and with no great inclination to the luminous surface, it is found to be unpolarized. But when the rays whose obliquity to the surface is very considerable are the subject of examination, they are found to be partially polarized. Tin; inference is, that these rays have been polarized by refmction; and hence that they must have originated beneath the surface of the luminous body. From the law of equality between the quantities of light simultaneously polarized by refraction and by reflection, it follows that there is a reflection toward the interior of such bodies, of some of the light which they generate. The light of flames and incandescent gases exhibits no s
Size: 2256px × 1107px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorsmithsonianinstitutio, bookcentury1800, bookdecade1840
