CRYSTAL STRUCTURE DETERMINATION. Isabella L. Karle, Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, D. C. 20375-5341, U.S.A

A rapid glance into the past will be presented describing some of the procedures and personalities that were involved in the dramatic changes that have taken place in the ease and scope of crystal structure analyses. The replacement of eye-estimation of intensities of diffraction spots on film by rapid automated data collection, the replacement of the desk calculator with supercomputers and associated computer programs, and the progression of structure determination from trial-and-error methods to Patterson and vector-search functions, to direct phase determination, particularly for structures lacking any atoms heavier than oxygen, have contributed to the rapid determination of structure, conformation and molecular assembly for molecules containing up to several hundred atoms. In retrospect, elements of processes were introduced into structure determination before they acquired a name in other arenas, such as the concept of "fuzzy logic" in practical phase determination and computer graphics representing molecules and mathematical functions.