The early days of the electron microprobe were characterized by the
variety of designs emerging from different laboratories in Europe, the
United States, and the USSR. Examples from Europe illustrate well the
diverging trends in the evolutionary process at that time. Later, commercial
pressures and a better understanding of user needs forced a rationalization
on both sides of the Atlantic, to the point where only few variants have
survived. These were memorable days, with scope for healthy rivalry and
vigorous debate.