Calendar: 1969-1970 Page 436

lxxiv Annual Report of the Delegacy as representative of London University In the course of the session he delivered two lectures to the University of London Geometry Seminar Professor Frohlich was Visiting Professor at Cornell University from September to January He gave colloquia and seminar lectures at Cornell University Ithaca the University of Maryland Brandcis University Massachusetts the University of Chicago the University of Toronto Michigan State University the University of Illinois the California Institute of Technology the University of Cali- fornia at Los Angeles the University of London Algebra Seminar and the University of Oxford He took part in the international conference on Ring Theory at Obcrwolfach Germany lecturing on Galois homo-morphisms class number and unit signatures groupoids and cohomology and Hermitian forms over rings with involution He gave post-graduate courses on Hermitian and quadratic forms at Cor- nell University and algebraic number fields in London University Dr Allan delivered lecture on 'Recent work on dynamo theory' at the Yorkshire Spring Mathematical Colloquim at Hull in May Dr Armitage gave seminar lectures at the Universities of Oxford Cambridge Nottingham Southampton East Anglia and at University College London He gave general lectures to branches of the Mathe- matical Association at Liverpool Durham and Southampton and also lectures at Rugby and Durham He gave postgraduate course in the University of London on 'Algebraic groups' Dr Erdos gave seminar talk at the University of East Anglia During July and August he was Research Associate at the University of Illinois Dr Higgins gave postgraduate course in the University of London on 'Lie algebras' Dr Laird was Senior Research Associate at the University of New Hampshire from September to January He delivered seminar lectures at Cornell University and Imperial College on 'The structure of the geomagnetic tail' and at Dartmouth College on 'Gyroreson- ancc' He was participant at the conference of the NATO Advanced Study Institute Roros Norway in April and presented an invited paper on 'Trapped particles' Dr Tims was Visiting Professor at the Weslyan University Connecticut for the session Dr Tyrrell lectured to the British Mathematical Colloquium on 'Rationality and unirationality' to the General Conference of the