Physicist. His contributions to science led to new theories on atomic structure. Son of a Lancashire cotton weaver, he began his career at Manchester University working with the New Zealand experimental physicist Ernest Rutherford. There, his findings were to inspire Rutherford to pursue his research into the structure of the atom. Marsden was in the final year of his degree course when he went to work with Rutherford's research assistant Hans Geiger, who was undertaking experiments for Rutherford on alpha particle scattering from thin foils. Marsden's subsequent finding that a few of the particles bounced right back came as a complete surprise, overturning current ideas of the structure of the atom. Rutherford was stunned and delighted at this result, helping inspire his subsequent nuclear model of the atom, in which most of its mass is concentrated in a minute, positively charged central nucleus. To quote Rutherford: "I suggested to one of my students, E. Marsden, that it would be of interest to examine whether any alpha particles were scattered in a backward direction from a metal plate. I did not have any good reason to expect a positive result." The publication of Geiger and Marsden's findings (now known as the Geiger-Marsden Experiment) can now be seen as one of the great moments of 20th century physics, making their names known to scientists worldwide. He was appointed Professor of Physics at Victoria College of the University of New Zealand in 1914 and after serving with the Royal Engineers in France during World War One (for which he received the Military Cross), he moved to New Zealand. He quickly acquired a reputation as an inspirational lecturer, with an energetic approach to ground-breaking research, and a talent for lobbying for financial support. In 1922, he became the Department of Education's Assistant Director, and, in 1926 the founding Secretary of the new Department of Scientific and Industrial Research. His science background and skills as a lobbyist and forward thinker, ensured the establishment of a department which could support all aspects of farming, New Zealand's main industry. He was elected President of the Royal Society of New Zealand in 1947, but moved to London four months later as New Zealand's Science Liaison Officer. He served on many committees throughout his life, and maintained his interest in research on radiation. Marsden returned to New Zealand in 1954, was knighted in 1958 and spent his retirement in Lowry Bay, on the shores of Wellington Harbour. For the last four years of his life he was confined to a wheelchair and cared for by his second wife.