Memoranda, on two papers 'The diffraction of sound pulses III. Note on an integral occurring in the theory of diffraction by a semi-infinite screen' and 'The diffraction of sound pulses IV. On a paradox in the theory of reflexion' by Frederick Gerard Friedlander Sectional Committee: Physics Recommended for publication in the 'Proceedings of the Royal Society of London'. Communicated by Max Born. Previous papers in the series by the same same author were refereed by Charles Herbert Lees and Edward Neville da Costa Andrade for confidential printing, with publication withheld until after the war. Should this procedure be followed in this case also? James Chadwick agrees. [Published in the 'Proceedings of the Royal Society of London'] Endorsed on recto as received 29 December 1941. 22 December 1941