Ernest Rutherford

At McGill University in Montreal, Rutherford worked with the chemist Frederick Soddy on thorium and its radioactive emanation, and their papers of 1902 and 1903 set out that radioactive substances change into other substances at a rate proportional to the amount present. The historian Helge Kragh describes the resulting disintegration theory as still counting as the fundamental law of radioactive change.

In May 1911 Rutherford published a paper in the Philosophical Magazine arguing that the large-angle scattering of alpha particles seen in Hans Geiger and Ernest Marsden's Manchester experiments required most of an atom's mass and charge to sit in a very small central body. New measurements by Geiger and Marsden, published in 1913, agreed well with the scattering formula he derived.

In papers published in 1919, Rutherford reported that alpha particles passing through nitrogen produced long-range particles which he concluded were probably hydrogen atoms, and he suggested that the nitrogen atom had been disintegrated in the collision. Eve and Chadwick's obituary says he did the experimental work himself, with William Kay's help in observing the scintillations.

In 1908-09, while Hans Geiger and Ernest Marsden were measuring how alpha particles scatter in thin metal foils, Rutherford suggested that Marsden look for alpha particles reflected directly from a metal surface. Marsden later wrote that he doubted Rutherford expected such a result and called the suggestion a hunch; Rutherford later recalled Geiger telling him in great excitement that some alpha particles were coming backwards.

The episode is consistent with a willingness to try an experiment whose outcome looked unlikely, a pattern that other accounts in this profile describe in different periods. Experimentation

On 7 March 1919, before deciding whether to stand for the Cavendish chair at Cambridge, Rutherford wrote to J. J. Thomson that he wanted a clear mutual understanding about the laboratory and its research students. Thomson replied that he would leave Rutherford an absolutely free hand in managing the laboratory, and Rutherford became its Director as well as professor.

The exchange is consistent with an interest in being responsible for a laboratory's direction, alongside the other evidence for leadership in this profile. Leadership Drive

In January 1907 Rutherford told Otto Hahn that he had been appointed to the chair and laboratory directorship at Manchester and would leave McGill that June, adding that he would be glad to be nearer the scientific centre because he felt America and Canada were on its periphery. At Manchester he went on to work with Geiger and Marsden on the scattering of alpha particles.