October 19, 1906-February 27, 1991
By Herbert A. Hauptman
The focus of Dave Harker's life, around which all his thoughts and actions revolved, was the science of crystallography, which he dearly loved. To crystallography he gave everything—his time, his energy, his total devotion. So complete was his dedication to this science and so fundamental and many faceted were his contributions that he influenced forever the course of its development. To this day, the Harker section and the Harker construction play essential roles in the determination of the structures of very large molecules. The Harker-Kasper inequalities provided the inspiration for a new branch of X-ray crystallography, the so-called direct methods of phase determination.
Dave was born on October 19, 1906, into a scientific and medical family. He grew up on the side of Mount Tamalpais in Mill Valley near San Francisco within view of the bay end of the Golden Gate Bridge. His father, George Asa Harker, who died when Dave was five years old, was a medical doctor from the University of California at Berkeley. Dave's father introduced the concepts of shape, symmetry, and structure into Dave's life. His earliest memories of his fa-