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 83
SAS ; thecurvature being measured by the sagitta AM. Themedium, however, retards the wave, and it will onlyhave gone as far as B instead of penetrating to A ; Bbeing a point such that BM = h . AM, where h is thevelocity-constant of the medium into which the wave enters.The curvature of the wave is… … Fig. 40. from B onwards being represented by the series of arcsdrawn from Q as centre. An eye situated in the mediumon the right of SS will perceive the waves as thoughcoming from O, the (virtual) point-image of P. Accuratelythe wave-fronts should be hyperbolic arcs, but if SS issmall relatively to…
Light · X-rays
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