Letter from Thomas Gold to Dr Ruth Gall, Head, Space Research Department, Instituto de Geofisica, Torre de Ciencias, Ciudad Universitaria, Mexico 20, D.F. Mexico Thanks her for her invitation to visit Mexico and visit the University of Mexico, and to give lectures on the subjects she suggested. Can stay two days and present three lectures. If two is all she wants, he will let her choose from; The Moon: A differentiated body or just the result of cold accretion? The solar wind: deep evaporation through the corona Pulsars and other dense stars. Sugggests November 11 and 12, or November 18 and 19. If neither suits, please to let him know. 5 August 1976