Report of the Annual Meeting Volume 1901 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 Excerpt: ...under the new conditions, i.e., within a self-contained rather, precisely the same undulation as existed during the first minute while P was emitting light. To this end let us imagine the undulation to continue its outward journey for any convenient period--say for two minutes after the annihilation of the contents of sphere p. This brings us to the epoch = three minutes. At this instant let reversal of all motions in the rather take place. The outflowing waves then retrace their steps, so that after the reversal the undulation becomes light converging towards the focus/. When the time t = eight minutes arrives the undulation has not only converged upon f, but after passing that focus it has become an undulation of divergent spherical waves, each part of the undulation when passing the focus having crossed to the opposite side of /. At the instant t = eight minutes let a second reversal of all motions in the rather take place. The light which, immediately before this second reversal, was diverging from f again becomes convergent, and within the period from = ten minutes to = eleven minutes each spherical wave for the second time passes the focus and becomes divergent, and each of these divergent waves now finds itself under such circumstances that so soon as it gets beyond little sphere p it becomes for all future time an exact repetition of what the corresponding actual wave emitted by P in the first minute was, and what it would have continued to be if neither reversal had taken place. Hitherto we have only dealt with the undulation as an undulation of spherical waves. Let us now go again over the same ground, and avail ourselves of its being legitimate to resolve the light into wavelets by Huygens's theorem. fa addition to little sphere p, let us draw ro...