Abstract
LONDON. Optical Society, October 9.—E. T. Hanson: Some problems in the theory of optical diffraction. A semi-infinite plane may be looked upon as a wedge the internal angle of which is zero. The application of KirchofFs formula in the latter case is considerably extended, it being shown that, through a region of not too small dimensions comprising the whole of the boundary of the geometrical shadow, the solution obtained is identical with the accurate solution. An expression is found for a plane wave incident at any angle upon a semi-infinite screen. An approximate expression is also found for the disturbance distributed over a straight slit due to a wave incident normally. KirchofFs formula has been applied, apparently for the first time, to an area of disturbance which is non-uniform.—W. M. Hampton: The annealing and re-annealing of glass. Relations connecting the strains present when cooling commences, strain due to gradient, and strain present after cooling, are obtained and the equations are applied to the case of slabs. The considerations affecting the temperature and conditions of annealing are discussed and tables giving annealing temperature, annealing time and rate of cooling for various kinds of glass are included.
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Societies and Academies. Nature 114, 631 (1924). https://doi.org/10.1038/114631a0
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DOI: https://doi.org/10.1038/114631a0