The story of etched particle tracks and their use in physical measurement in geology, anthropology, archeology, nuclear studies, space science and cosmology. The author discusses the impact of this discovery on the course of scientific investigation. He writes from his close proximity to the events described, and encompasses the social and administrative history of this discovery, the relationships between the principal figures involved, collaborations, travel, and research habits. Prominently mentioned are R. M. Walker, P. B Price, and R. L. Fleischer.