Letter from [Egon] Orowan, University of Cambridge, Department of Physics, Cavendish Laboratory, Free School Lane, Cambridge, to Professor [Edward Neville da Costa] Andrade, F. R. S., Director, The Royal Institution, 21 Albermarle treet, London, W. 1. Notifies he was unable to ask Professor Mathewson about the importance of [Albert Marcel Germain René] Portevin's work, as he had to cancel his trip to Newhaven. He was instead able to ask Professor Bever of the Metallurgy Department of M. I. T., who told him that Portevin has made very important contributions to the metallurgy of steel in particular. As many of these contributions have become the anonymous stock-in-trade of the text books, they are no longer associated with Portevin. 10 July 1950