Ernest Marsden

Ernest Marsden

One day Geiger came to me and said, "Don’t you think that young Marsden … ought to begin a small research?" Now I had thought that too, so I said, "Why not let him see if any α-particles can be scattered through a large angle?" … Then I remember two or three days later Geiger coming to me in great excitement and saying, "We have been able to get some of the α- particles coming backwards …". It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you.

Ernest Rutherford describes the work of his student, Ernest Marsden, in ‘The development of the theory of atomic structure’, Joseph Needham and Walter Pagel (eds), Background to Modern Science, Cambridge University Press, 1938, p68.

Ernest Marsden is best known in New Zealand as the first secretary of the Department of Scientific and Industrial Research (DSIR), a position he held from 1926 to 1947. Internationally, however, he is remembered for his role in Ernest Rutherford’s work on the structure of the atom.

In 1909, as a 20-year-old student at Manchester University, Marsden observed that a tiny fraction of alpha particles fired at a thin gold foil were deflected straight back. Rutherford used this result to determine a new structure of the atom, with most of its mass concentrated in a minute central nucleus.

In 1915, on Rutherford’s recommendation, Marsden came to New Zealand to be professor of physics at Victoria University College in Wellington. In 1922, he turned from research to bureaucracy. He first became assistant director of education then, in 1926, was appointed secretary of the DSIR, where colleagues described his ‘infectious enthusiasm’ and ‘irrepressible optimism’.

The young DSIR’s focus was on assisting primary industries but Marsden retained his interest in physics. During the Second World War he set up a team to develop radar equipment for use in the Pacific war. He also used his scientific connections to get a team of young New Zealand scientists onto the American Manhattan Project to develop an atomic bomb, and the British-Canadian project to develop atomic energy. Unable to participate in the nuclear research programme himself, Marsden directed his enthusiasm to a search for uranium in New Zealand.

Marsden had a post-war vision for a nuclear New Zealand, where scientists would create radioisotopes and conduct research on a local nuclear reactor, and industry would provide heavy water and uranium for use in the British nuclear energy and weapons programmes, with all these ventures powered by energy from nuclear power stations. His vision was not realised but, in 1946, he established a team of scientists to carry out fundamental and applied atomic research and advise on atomic energy and the application of isotope techniques to problems in agriculture, health and industry. This eventually became the DSIR’s Institute of Nuclear Sciences.

In 1947, Marsden left New Zealand to become the DSIR’s scientific adviser in London. He retired and returned to Wellington in 1954, but continued to work, travelling extensively, serving on numerous committees and conducting research into environmental radioactivity. Through his studies on the impact of radioactive bomb fallout, he came to oppose the continued development and testing of nuclear weapons.

In 1966, the year France began testing nuclear bombs in the Pacific, a stroke left Marsden confined to a wheelchair and, in 1970, he died.  

By Rebecca Priestley

Medals and awards

FNZI 1922, CBE 1935, FRS 1948, Knight Bachelor 1958

Further reading

Sir Ernest Marsden 80th Birthday Book, AH & AW Reed, 1969

Ross Galbreath, DSIR: making science work for New Zealand, Victoria University Press, 1998

Ernest Marsden biography – Dictionary of New Zealand Biography website

Permission of the National Library of New Zealand Te Puna Mātauranga O Aotearoa, must be obtained before any reuse of this image

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