Canadian, c.1938, an archive of images from the estate of Albert Prebus, including the original first image ever captured by the prototype electron microscope, image on card backing with the following handwritten note ‘The very first picture recorded with Toronto electron microscope early in 1938. Aluminium foil across specimen holder. Magnification approximately x100’, along with a larger copy of the same image, with an archive of related items including various images of the microscope and an original copy of the 'PROGRAM OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR OF PHILOSOPHY’, of Albert Prebus, B.Sc (University of Alberta) 1935, M.Sc. (University of Alberta) 1937, Wednesday, May 20th, 1940.

The Toronto University Transmission Magnetic Electron Microscope: Many important scientific discoveries can trace their origins to the Physics Department of the University of Toronto. Perhaps though, no discovery there has been quite as significant to science and society as the building of the first transmission magnetic electron microscope by two graduate students, James Hillier and Albert Prebus in April of 1938 under the direction of the Department Chairman, Professor E.F. Burton.

For at least 10 years prior to the instrument being built there had been various attempts to construct a working transmission electron microscope. In Europe Hans Busch’s 1926 paper showed that theoretically an electron beam could be focused by using a coaxial magnetic or electric field. Prior to this Louis de Broglie had hypothesised that electrons possessed wave properties which suggested that not only was the principle of an electron microscope possible it may give a greater magnification than an optical instrument. In Germany at the Berlin Technische Hochschule Ernst Ruska and his colleagues had designed the equipment necessary to concentrate a magnetic field. This discovery led Ruska to develop an early version of a two-stage transmission electron microscope. However, the instrument he designed and built only just achieved a resolution better than an optical instrument. By 1933 a number of other scientists had developed similar instruments all with disappointing results. Only the instrument built by Ruska was able to produce micrographs and these were of poor resolution.

It was Professor E.F. Burton, Chairman of the Department of Physics at the University of Toronto who was to become the moving force behind the project to build a working magnetic transmission electron microscope. During the autumn of 1935, on returning from a conference in Berlin on the possible applications of an Electron Microscope, he met Cecil E. Hall, from the University of Alberta. Hall was hoping to do graduate work in the field of spectroscopy. Burton managed to convince Hall to change his interests in spectroscopy to electron optics. This would mean that Hall would be the first graduate student in this new field. Burton later convinced Prebus to follow the same route.

Hall constructed two early forms of emission microscopes, the second of which used a magnetic lens which allowed him to take a photograph of the emitting surface of the hot cathodes at an impressive 3000x. It was for this early work that, in 1936, he received an M.A. Due to a lack of funding for the project Hall left and ended up working for Kodak. However, the seeds were now sown and Burton was determined to build a working Electron Microscope.

It was in the Autumn of 1937 that Albert Prebus, who already had an M.Sc. from the University of Alberta, came to Toronto university to continue his interest in atomic spectra. Burton, as with Hall previously, convinced him to change his interests over to this still new field of electron optics. Burton wasted little time in teaming him up with James Hillier, a B.A. graduate who had been working on Burton’s electron microscope project since graduation. Both Prebus and Hillier, highly intelligent, hardworking, and enthusiastic towards the project, worked well as a team. Their aim was to build a compound transmission magnetic electron microscope with a view to applying it to biological and colloidal materials. To do this and bring the project to fruition they had only the work done by Hall and his prototype instruments, translated publications by Knoll, Marton & Ruska, and their own wits and skills.

Prebus and Hillier submitted the working drawings at the end of the Christmas vacation of 1937 and active construction started in January of 1938. Both Hillier and Prebus designed, machined and constructed most of the microscope. The microscope was completed after 4 months of long hours. Then in early 1938 the first image or micrograph was taken. The microscope was improved and its magnification increased finally resulting in images taken at 20 Å or better.

Burton reported the success of the project to the university as “Mr. James Hillier, assistant demonstrator and Mr. Albert Prebus, holder of a studentship from the National Research Council have continued the work of perfecting the electron microscope and have succeeded in taking many photographs of submicroscopic structures up to a primary magnification of 30,000 times". Just one year after work had begun on the project the first scientific report was published by the Canadian Journal of Research in January 1939. In December 1939 the first micrographs were published in the popular magazine Saturday Night with a descriptive text by Burton. In 1939 the Book by Burton & Kohl, authored by the journalist R. E. Beamish was published describing the microscope built in 1938.

The original prototype microscope is now in the collection of the Canadian Science and Technology Museum:
Physics Department Donates Electron Microscope to Canada Science and Technology Museum - https://www8.physics.utoronto.ca/physics-at-uoft/history-old/the-electron-microscope/physics-department-donates-electron-microscope-to-canada-science-and-technology-museum