In the mid 1950s, after completing the DNA structure, James Watson and Francis Crick considered the structure of small viruses. On largely theoretical grounds, they conjectured that small viruses might be built from multiple copies of a single subunit arranged in a symmetrical way, much like a crystalline structure. At the same time, Donald Caspar and Aaron Klug began using x-ray diffraction to probe viral substructure. Their data supported the Watson-Crick hypothesis, but early electron micrographs of viruses taken by the microscopist, Robert Home, and the medical virologist, Peter Wildy, among others, indicated that there might be more subunits in the structure than the Crick-Watson hypothesis allowed. Caspar and Klug began to search for a theory of virus structure which would reconcile the theoretical considerations of Crick and Watson with the empirical observations. They were inspired by the architecture of Buckminster Fuller and his geodesic dome structures. Very roughly, their theory proposed that "spherical" viruses were constructed like miniature geodesic domes. This theory is still thought to explain the structure of the majority of spherical viruses, although some exceptions were subsequently discovered. Aaron Klug received the 1983 Nobel prize, in part for his work on viral structure. The author of this dissertation research project plans to write the first detailed history of this interesting episode in the history of science. This NSF grant will allow him to travel to Cambridge UK, to spend a month in Aaron Klug's laboratory, to interview him, catalog the many physical models he and his collaborators built to illustrate his ideas, examine his notes from the period, and also to interview Robert Home, a number of collaborators, and Jo Wildy, the wife of Peter Wildy. (Tragically, Peter Wildy is deceased.) It will also allow a trip to the Buckminster Fuller Institute Archive, where among other things, the correspondence between Buckminster Fuller and Klug and Caspar is preserved, and the California Institute of Technology Archive. Donald Caspar and James Watson spent the first year (1954) of their analysis of virus structure at Caltech. And finally, it will allow Donald Caspar to be re-interviewed and his research notes analyzed once the detailed history is more complete.