Dr. Immanuel Estermann was engaged in writing a book on the History of the Molecular Beam Method when he died in Haifa, Israel on 31 March 1973. The original plan of the manuscript was to cover three distinct historical periods: the first, the years 1911–1933, when the center of research in molecular beams was at the University of Hamburg; the second, from 1933 to the outbreak of World War II, when the most active laboratory working in the field was at Columbia University; and the postwar period, when many laboratories on both sides of the Atlantic became actively engaged in this field. The material in this paper deals primarily with the early historical period and would have formed the essence of the first two chapters of the book. In addition to presenting interesting historical facts on a crucial period in the development of quantum physics, it contains some amusing historical sidelights on the research personalities that dominated that period.