Six lectures on light : delivered in America in 1872-1878 (1886)
Tyndall, John, 1820-1893 · New York : D. Appleton · leaf 179
e cone passes along the axis, this ray only will escapedouble refraction. Each of the others will he dividedinto an ordinary and an extraordinary ray, the onemoving more slowly through the crystal than theother; the one, therefore, retarded with reference tothe other. Here, then, we have the… … upon the screen a beautiful system of iris-rings sur-rounding the end of the optic axis, the circular bandsof colour being intersected by a black cross (fig. 47).The arms of this cross are parallel to the two directionsof vibration in the polarizer and analyzer. It iseasy to see that those rays…
Light
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