EDWARD CRISP BULLARD (1907-1980)

Sir Edward Bullard, universally known as Teddy, was born in Norwich, England, on September 21st, 1907, into a wealthy family whose prosperity derived from brewing. Although his father intended him to become an accountant and join the family firm, Teddy was deeply influenced late in his school career at Repton (an English Public School) by A.W. Barton, a teacher of physics who had worked under Rutherford at the Cavendish. With Barton's help, Teddy entered Cambridge University in 1926; he was awarded a first class degree in Natural Sciences and, in 1929, he himself began as a research student in Rutherford's laboratory. His graduate work was mainly experimental--to determine the scattering cross-section of low-energy electrons in various gases. His student scholarship having run out in 1931, and having married, Teddy was faced with rather dim prospects for employment at the height of the depression. An unlikely opportunity presented itself--Sir Gerald Lenox-Conyngham, the head (and sole member) of a newly formed Department of Geodesy and Geophysics was seeking an assistant. On Rutherford's advice, despite serious misgivings, Teddy took the position of demonstrator. He quickly finished his Ph.D. and began a career in geophysics.

In the years before the Second World War, Teddy mounted field programs in three of the four major divisions of geophysics. Having refined pendulums to achieve an accuracy of better than one part in a million, Teddy took them to the East African Rift to measure gravity there. This, his first geophysical project, already characterized his bold attack on major questions, in this case the process that formed one of the world's greatest continental structures. At the suggestion of the influential American geologist Richard Field, whom he had met in Edinburgh in 1936, Teddy initiated a marine seismic refraction program, with instruments of his own construction deployed from chartered trawlers. Together with Maurice Ewing's work on the other side of the Atlantic, these studies marked the first serious marine geological investigations, showing thick wedges of sediment under the continental shelf; almost without exception up until this time, geologists had been content merely to speculate about the nature of Earth under the sea. As we now know, the marine realm held the key to a deeper knowledge of the whole Earth. The third topic receiving Teddy's attention was the measurement of the heat flowing from the Earth; he fundamentally improved the measurement techniques and then mounted a major observational expedition to South Africa.

During the War, Teddy worked in the British Admiralty with remarkable effectiveness, primarily to protect ships from German mines. A major achievement was the successful `degaussing' of the fleet by laying current-carrying wires inside the hulls, thus neutralizing the induced vertical magnetization of the steel ships and rendering them much less detectable to magnetic mines. Losses to mines of all kinds fell from being a major factor to only one-tenth of those suffered from submarine attack, largely as a result of the efforts of Teddy and his team.

Upon returning to Cambridge after the war, Teddy found no sympathy on the part of the University for his plans to expand geophysics. In frustration, he accepted the Professorship of physics at Toronto University, but stayed only one year, departing in 1949. While there he began his work on the Earth's magnetic field, thus penetrating the fourth major branch of geophysics. Teddy clearly nursed his ambition to create a geophysical Cavendish laboratory at Cambridge, but it was obvious to everyone that the time was not ripe. He returned to England as head of the National Physical Laboratory, the British equivalent of the National Bureau of Standards in the U.S. Here he proved himself a deft administrator, supporting the NPL in a variety of successful programs, including the development of digital computers and numerical methods for them, and the establishment of atomic standards for frequency and time. And yet he found time to write some of his most important papers. He carried out theoretical studies of the self-exciting dynamo (using methods closely paralleling those used for calculating quantum transitions in atoms) and backed them up with extensive numerical calculations on the early digital computers. This work was profoundly influential in the field and encouraged a flourishing of dynamo theory, which continues to this day; the original idea of Lamor had been effectively suppressed by Cowling's `anti-dynamo' theorem in 1933; Teddy realized that Cowling's theorem was far from universal in its applicability and his inspired work convinced everyone else of this. While visiting Scripps Institution of Oceanography, he continued his experimental work into heat flow, now making the most important advance--the taking of observations of heat flux through the ocean floor. These revealed the puzzling fact that the flux was at least as great as that on the continents, yet radioactive heat sources were virtually absent in the oceanic crust.

At last, in 1956, Teddy perceived the opportunity to return to Cambridge and realize his ambition. He left the NPL to return to the Department of Geodesy and Geophysics rising to the position of chair bu 1964. It is accurate to say that Teddy's own scientific publications in the period 1960-1974, when he ran the department, were not as significant as his earlier ones. But he presided over and made possible the British contribution to the revolution in Earth sciences that took place in the 1960s. He guided the main work of the department into the study of marine geology, whose unraveling he understood would be the crowning achievement of twentieth century geophysics. So many major discoveries came from the Cambridge laboratory in the late 1960s: Fred Vine and Drummond Matthews discovered sea-floor spreading and interpreted the magnetic stripes; Tuzo Wilson understood transform faults while visiting; Dan McKenzie explained the origin of the high oceanic heat flow and formalized plate tectonics. It is no exaggeration to say that Madingley Rise was the geophysical Cavendish of the 60s and 70s and Teddy was its Rutherford.

In 1974, Teddy reached Cambridge University's mandatory retirement age and at once moved to a professorship at the University of California, San Diego. Scripps Institution of Oceanography had become a second home to Teddy after the war. Beginning in 1949, he visited Scripps quite regularly in the summer months, where he carried out some of his most important experimental work on marine heat flow. For a number of years, he taught Earth sciences at UCSD to nonscience majors with great enthusiasm, although his health was already failing. His last paper, with Stuart Malin, entitled The history of the Earth's magnetic field at London 1570-1975, was completed the day before he died, and his last act was to write the letter communicating it to the Royal Society.

An official history does little to convey the side of Teddy that endeared him to those of us lucky enough to know him: his unfailing common sense, his good humor at all times, his indifference to rank, and his remarkable generosity, particularly to his students and junior colleagues.

J. Freeman Gilbert
John A. Orcutt
Robert L. Parker
University of California, San Diego