Harriet Brooks Pitcher
1876-1933

Harriet Brooks was a pioneering nuclear physicist at a time when it was extremely difficult for women to pursue careers in science. Under the direction of famed physicist Ernest Rutherford at McGill University, she investigated the behaviour of the radioactive element radium. Brooks and her team discovered that it decayed into a new element, which was eventually named "radon". A few years later, she performed experiments which showed that radon transformed in a similar way. This was known as "transmutation of the elements," and laid the foundation for understanding radioactivity and the structure of the atom.

In 1906, while working as a tutor at Barnard College in New York City, Brooks became engaged. At the time, married women resigned their positions both as a matter of course and because of university policy. Although Brooks eventually broke this engagement, she resigned anyway, perhaps defeated by the resistance she faced. She went to Paris to work with Marie Curie. Soon after, she married Frank Pitcher in London, and gave up physics entirely. She died in 1933, likely of leukemia. The dangers of working with radioactive substances were not known at the turn of the century, and pioneering nuclear physicists did not wear protective clothing. Although her career lasted a scant thirteen years, Brooks was able to make fundamental contributions to nuclear physics — a feat rarely matched even in careers that last a lifetime.

James Hillier
b. 1915

As a boy, James Hillier thought he would like to be a commercial artist. Instead, he turned out to have a talent for mathematics and physics, and won a science scholarship to the University of Toronto. There, he and fellow student Albert Prebus invented the world's first practical electron microscope.

Electron microscopes work by focussing a beam of electrons, rather than a beam of light. The wavelength of electrons is much smaller than the wavelength of light, enabling greater magnification and depth of focus. In 1938, Hillier and Prebus produced a microscope that worked by passing a beam of electrons through a carefully prepared sample. The beam was then focussed on a photographic plate. Their device magnified objects to 7,000 times their size — optical microscopes produced a magnification of only 2,000 times. A few years later, Hillier and two other physicists developed what was arguably the first scanning electron microscope. This worked by scanning the object with a beam of electrons to produce an image similar to the one on a television screen.

After he retired, Hillier devoted himself to promoting science education. He now gives talks to high school students about careers in science. Because he would never have been able to go to university without scholarships, he established the James Hillier Foundation, which awards scholarships to promising science students in his hometown of Brantford. His work has brought him many honours, including the Order of Canada.

John Tuzo Wilson
1908–1993

As a young man, John Tuzo Wilson helped mount an expedition to the Canadian Arctic to show that long-distance travel was possible there. Other scientists soon followed his example, opening up the Canadian North to scientific exploration. He made even greater scientific contributions to the theories of plate tectonics and continental drift. In 1960, the continental drift theory remained problematic. One of its difficulties was that it could not explain why active volcanoes sometimes occurred quite far from the nearest plate boundary. Wilson proposed that volcanic island chains could be formed by the movement of a plate over a stationary "hotspot" of rising magma. He also suggested that, if two plates slid past one another, they could form a transform fault, such as the famous San Andreas Fault. With these contributions, Wilson considerably strengthened the theory of continental drift, and became well-known in geophysics circles.