. The optical indicatrix and the transmission of light in crystals. though the geometrical See also puges 7, ;. - Mem. pr^s, a Ilnstitut: Paris, 1811, vol. 2, p. 413 18 THE TRANSMISSION OF LIGHT IN CKYSTALS. representation of the laws of transmission of light in biaxal crystals wassuggested to Fresnel by ideas in which .elasticity had a gieat part,the possible existence of such crystals, and the corresponding laws oftransmission of light, might have been deduced from the above by a simplegeneralisation, involving no reference either to the constitution of theluminiferous ether or to the n
. The optical indicatrix and the transmission of light in crystals. though the geometrical See also puges 7, ;. - Mem. pr^s, a Ilnstitut: Paris, 1811, vol. 2, p. 413 18 THE TRANSMISSION OF LIGHT IN CKYSTALS. representation of the laws of transmission of light in biaxal crystals wassuggested to Fresnel by ideas in which .elasticity had a gieat part,the possible existence of such crystals, and the corresponding laws oftransmission of light, might have been deduced from the above by a simplegeneralisation, involving no reference either to the constitution of theluminiferous ether or to the nature of the physical change involved in thetransmission of light; and further, that the step was so natural a one totake that the discovery of the true form of the wave-surface for biaxalcrystals could scarcely have been long avoided. Another mode of r/cometncallij reprcsoitiug the churacters of the extra-ordiiiarih/ refracted ra^, hij reference to the same upheroid, natundhj presents itself. Draw OFii parallel to rj (Fig. 3), the tangent at r^ to the ellipse in. which the spheroid is cut by the plane r^OC; OU^ and Or^ arc said to be conjugate to each other, and the tangent at 11^ is parallel to Or^. By a well-known property of the ellipse, the area of the parallelogram of which OBx, Qr^, are adjacent sides is constant, whatever the direction of Orj: hence the area is OA • OG ; OA and 00 being the principal axes of the ellipse, and therefore conjugate to each otlier. But if /.,.\i is perpendicular to O/-,, meeting it in A,, and is thus normal to the ellipse and therefore also to the spheroid at ii\, the area of the parallelogram is also Or^Il^X^. OAOCHence O/-, = -^^-, whatever the direction of Or^: and fMOC being a constant quantity, the reJociti/ of a ray transmitted in the direction O/-, maybe represented, not only by Or^, but by the iuNerse of h\^\. But tlu^ REPRESENTATION BY MEANS OF THE SPIIKROID ALONE. If) same line FiiXi determines the 2)lnne of pohirisation of tlie
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherlondo, bookyear1892
