AbstractThis somewhat unlikely combination of subjects came together at a Symposium in Vienna in March, 1967, and Mr. J. F. Bell, who attended the Meetings, sent us a report from which the following short notes have been compiled. The common denominator was Dr. Tengstrom who presides over each of the relevant I.A.G. study groups and wished to review the state of the art in both topics before the XIV I.U.G.G. General Assembly at Lucerne.