A new technic is invariably surrounded by an aura of almost ritualistic mystique that can only gradually be eroded by the passage of time. One can imagine that after several decades of exhaustively controlled and supervised rocket launches, the day will come when an untidy, out-of-breath passenger, carrying his luggage in a plastic bag, will demand to know if he has missed the 8 a.m. moon bus. An example of just such a lowering of initial standards can be seen today in the field of electron microscopy. Early electron microscopes were such fragile and temperamental machines that by far the . . .