Notes from lectures by W.R. Piggott. The material consists of a hardcover springback folder containing 75 pages, plus a 3 page appendix typescript account with lists of references and contents, beginning 'The following appendix consists fundamentally of notes taken by myself at a series of lectures delivered by Mr. W.R. Piggott of D.S.I.R. [Department of Scientific and Industrial Research] in October 1944'. The account is not signed, and there are manuscript corrections in more than one hand.