Light visible and invisible : a series of lectures delivered at the Royal Institution of Great Britain, at Christmas, 1896 (1897)
Thompson, Silvanus Phillips, 1851-1916, Royal Institution of Great Britain · New York : Macmillan · leaf 156
ch, when the analyser is rotated, changes Ill POLARISATION OF LIGHT 135 to a white cross. This black cross is visible in the darkfield. Such black crosses one obtains whenever theobject is one having different rigidities in the radialand tangential directions. The next slide shows it evenbetter.… … Fig. 94. operation of crystallising starts at a number of inde-pendent centres, around which little groups of crystalsgrow with a radial structure and a circular outline. Astheir axes of maximum elasticity all point radially tothe centre around which they grew, the maximumresolution of the wave…
Light · X-rays
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