Letter from Margot Thomson, to John David Griffith Davies, regarding 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 Acknowledges receipt of the six copies of the paper, at the request of Professor Thomas. [Published in the 'Proceedings of the Royal Society of London'] Endorsed on recto as received 14 January 1943. 12 January 1943