Letter to Geoffrey Ingram Taylor, regarding two papers 'The air wave surrounding an expanding sphere' by Geoffrey Ingram Taylor, and 'The diffraction of sound pulses III. Note on an integral occurring in the theory of diffraction by a semi-infinite screen' by Frederick Gerard Friedlander Sectional Committee: Physics The paper, once regarded as confidential, is soon to be published in the Proceedings. If he requires author's copies, please correspond directly with Cambridge University Press. [Published in the 'Proceedings of the Royal Society of London'] No received date. 3 July 1946