Leonard F. Fuller and Naval Radio in 1916
The June 1916 issue of the PROCEEDINGS OF THE IRE (Institute of Radio Engineers) included a brief contribution on the reception of continuous wave signals by a brilliant young electrical engineer, Leonard F. Fuller. The same issue contained a paper by Louis W. Austin, head of the U. S. Naval Radio Laboratory, reporting on radio propagation experiments at the naval radio station at Darien in the Panama Canal Zone. The two papers were not unrelated since Fuller was the chief electrical engineer of the Federal Telegraph Company, which had recently constructed a 100 kW Poulsen-arc transmitter for the Darien station. In 1916, the Navy was in the process of installing high-power arc converters designed by Fuller at strategic locations around the world.

Fuller was born in Portland, Oregon, in 1890 and graduated in engineering from Cornell University in 1912, having constructed a Poulsen-arc transmitter as a senior thesis project. In September 1912, he joined the Federal Company located in Palo Alto, California, and, despite his youth, was appointed chief electrical engineer the following year. He immediately confronted the challenging assignment of filling Navy contracts for 100 kW arc converters. The Federal Company had acquired the American rights to the oscillating arc converter from the Danish scientist, Valdemar Poulsen, in 1909. Cyril F. Elwell, Fuller’s predecessor as chief electrical engineer at Federal, had designed arc converters with a power of 30 kW but had failed in an effort to construct a 60-kW unit. Fuller initiated and led an intensive research effort at Federal that produced a deeper understanding of the arc converter and the design information needed to construct the higher power units demanded by the Navy. For example, he found that there was an optimum magnetic field for each set of operating conditions and that the magnitude of alternating current should equal the direct current for optimum conversion efficiency. A strong magnetic field was required to extinguish the arc once each cycle of the high-frequency output current.

The success of the Darien 100-kW transmitter led to Navy contracts for arc converters of even greater power. During 1917, a 200-kW arc unit was installed at a Navy station in San Diego, California, and 500 kW arcs were installed at Pearl Harbor, Hawaii, at Cavite in the Philippines, and at Annapolis, Maryland. Early in 1918, Federal signed a contract to supply a 1000 kW arc converter to be located near Bordeaux in France. The 500 kW converters weighed about 60 tons, while the 1000-kW unit weighed about 85 tons. In physical appearance these machines resembled large turboelectric generators, although they had no rotating parts and were quite rugged and durable. Federal also supplied the Navy with smaller arc sets suitable for use on ships. By 1918 the Navy operated a network of high-power arc transmitters that enabled immediate communication with its ships in the Atlantic, Pacific, and Caribbean.

This case history of developments three quarters of a century ago relates to several themes in contemporary history of technology. The acquisition of the Poulsen arc invention by Federal is an example of technology transfer from Europe to America that would be repeated, for example, by the transfer of the resonant-cavity magnetron to the United States in 1940. The history of the arc converter during the first World War is a good example of what historians now call “military enterprise.” Military communication needs and prescribed technical specifications stimulated development of continuous-wave radio in general and the high-power arc oscillator in particular. Pressure from the Navy forced Fuller and his assistants at Federal to generate a body of engineering science as applied to arc converters when the existing technical literature proved inadequate for the design of converters of more than 30 kW power capability. Historians of technology recently have stressed distinctions between science and engineering and related distinctions among types of knowledge such as basic science, engineering science, and engineering design.

Leonard Fuller earned his doctoral degree from Stanford University in 1919 and left Federal the same year. He went on to enjoy a successful career as a consulting engineer with several companies. He also held academic positions at the University of California and Stanford. The IRE awarded him the Morris N. Liebman award in 1919 for his research on the high-power arc converter, and he became an IRE Fellow in 1925. He died in 1987 at the age of 96.
James E. Brittain
School of History , Technology and Society
Georgia Institute of Technology

Submitted by Bob Morrison, Editor

Copyright 1991 IEEE. Reprinted with permission from the IEEE publication, “Scanning the Past” which covers a reprint of an article appearing in the Proceedings of the IEEE Vol. 79, No.6, June 1991.