Preston, Thomas, Joly, Charles Jasper, 1864-1906, Parsons, John Herbert, Sir, 1868-1957, donor, University College, London. Library Services · London : Macmillan and Co. · leaf 289
a small hole half covered with a thin transparent plate, has been mentioned already in Art. 106. We are now in a position to easily deduce the expression for the illumination at any point, the aperture being sup- posed rectangular. Let AB (Fig. 137) represent the plate covering half the aperture… … Fig. 138. traverse the plate will be accelerated relatively to that which passes through the plate by some amount 2S. Hence the effect of the free part BC of the aperture will be represented by the arc BC = 2a (Fig. 138) of the circle, where AB = 28, the retardation in the plate. It follows easily…
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