The Electron Microscope

While there is little doubt that a German physicist developed the basic principles of the electron microscope, both Canada and the United States claim to be first in making it practical. The evidence, however, clearly favours Canada as two postgraduate students working in the Physics Department of the University of Toronto with their physics professor, between 1937 and 1939, developed the first ever transmission electron microscope.

The original electron microscope as developed in 1938 in McLennan Laboratories of the University of Toronto is now on permanent exhibition at the Ontario Science Centre, Toronto, Ontario

The reason for the dual claim is straightforward. Following graduation with a Ph.D. in 1940, one of the students, James Hillier,joined Radio Corporation of America (RCA) at Camden, New Jersey. Here he reaped recognition for adopting the design of the University of Toronto microscope and developing it into the prototype for the RCA production model. The commercial electron microscope for RCA was supervised under the watchful eye of a Russian-born scientist, vice president of the corporation.

Albert Prebus, left, had just received his M.Sc. from the University of Alberta and James Hillier was a graduate student in mathematics and physics at the University of Toronto when they were asked by Professor E.F. Burton, Director of the Physics Department, the University of Toronto, to undertake the construction of a high-voltage magnetic compound electron microscope with the aim of applying it to the investigation of biological specimens. When the electronic microscope was completed in 1938 by the budding spectroscopists, it was the first of its kind in North America. Both the National Research Council and the Banting Institute funded employment for the two workers during the summer of 1938.

Hillier, a native of Brantford, Ontario, was doing postgraduate work at the University of Toronto, under Professor Eli Burton, a native of Green River, Ontario, when he was commissioned along with Albert F. Prebus of Edmonton, Alberta, another University of Toronto postgraduate student, to work on the electron microscope project in the fall of 1937. A physics professorat the University of Toronto since 1922, Burton was head of the department when he visited Ernst Ruska at the Berlin Technische Hochschule in 1935 where he saw first hand the pioneer two-stage transmission model achieving image resolutions beyond that of the light microscope.

The electron microscrope is capable of magnifying biological specimens up to one million times. These computer enhanced images of 1. smallpox, 2. herpes simplex, and 3. mumps are magnified, respectively, 150,000, 150,000 and 90,000 times.

As one of Burton’s major interests was colloids — substances such as smoke composed of particles, some of which were invisible even under the best of optical microscopes — he decided upon returning home to try improving on the microscope he had seen in Germany. He selected two of his brightest students to undertake the job.

They both knew that, in principle, a microscope using electrons had the potential of surpassing optical models since the wavelengths of speeding electrons is much smaller than the wavelengths of light which meant an electron microscope would havethe ability to reveal much smaller objects than could be observed through optical units which, in the late ‘30s, could magnify particles up to 2,000 times their size.

In early 1938 — a mere four months later — the University of Toronto team of Hillier and Prebus, under Burton’s supervision, proved them right when they tested their machine using a simple razor blade edge. Viewed through an optical microscope the edge looked relatively sharp; under their electron microscope, the same edge looked like a jagged mountain range as the microscope showed the razor’s edge 7,000 times its size. Another year was spent on further refinements to the unit before both students completed their post-graduate studies and took jobs in the United States.

Hillier went to RCA where he developed electron microscopes for commercial use under Vladamir K. Zworykin, a Russian-born scientist who, according to the World’s Who’s Who of Science is credited with several inventions leading to television as well as the electron microscope. In the Who’s Who of Science, however, Hillier is identified as the “builder of the first successful high resolution electron microscope in the Western Hemisphere, 1939-40,” a statement supported by the late Issac Asimov, one of America’s most respected authors on science, who wrote in his Guide to Science, “... the first really usable one was built in 1937 at the University of Toronto.”

Hillier also wrote a number of papers about the development of the electron microscope while at RCA, and later became president of the Electron Microscope Society of America as well as the National Society of Engineers in the United States. He was also the recipient of the Albert Lasker Award, the David Sarnoff Founders Medal and is a member of the National Inventors Hall of Fame.

Prebus, for many years a professor of Physics at Ohio State University, proceeded in 1940 to design and construct an electron microscope shortly after receiving a post-doctoral position there. He played a major role in the incorporation of the Electron Microscope Society of America in 1942.

Professor Burton, whose entire career was spent at the University of Toronto, served as a member of the National Research Council from 1937 to 1946, and was involved in secret research on radar during World War II. Shortly after his death at age 69 in 1948, the Electron Microscope Society of America held a special meeting in Toronto dedicated to the memory of Professor Burton — in recognition of his pioneering work “in introducing the art and instrumentation of electron microscopy to the western hemisphere.” In 1973, the same society introduced an award in his name — the Burton Medal — to be awarded annually to a promising young scientist in the field of electron microscopy.