An elementary treatise on optics / by I.W. Jackson.

  • Jackson, I. W. (Isaac Wilber), 1804-1877.
Date:
1867
Catalogue details

Licence: Public Domain Mark

Credit: An elementary treatise on optics / by I.W. Jackson. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    same plane; and the interference of two rays thus polarized, is the case already considered in article 126. The non-interference of two rays polarized in planes at right angles to each other [Art. 172, 2°], is also an obvious consequence of the theory. It is also a mathematical deduction from the theory, that while the intensity of the resulting light, in the case of two rectilinearly polarized rays, whose planes of polarization are at right angles to each other, is constantly equal to the sum of the intensities of the separate rays, the nature of the vibration varies with the phase in which the two rays meet: thus it is found, that when the rays differ in phase by an exact number of semi-undulations, the resulting vibrations will still be rectilinear; that when they differ by an odd multiple of a quarter of an undulation, they will be circular; and that in all other cases, they will be elliptical, the axis of the ellipse retaining constantly the same direction. When the molecules thus vibrate in an ellipse, the light is said to be elliptically polarized; when in a circle, to be circu- larly polarized. But this elliptically polarized light of the theory is found to be identical in its properties with the elliptically polarized light of Doctor Brewster. We conclude, then, that the most general form of polarized light is that in which the molecules of the ether vibrate in ellipses whose planes are per-