At first he was interested in a career in medicine, but later in the year Kerr Grant, the physics professor, offered him a cadetship in the Physics Department. It paid 10 shillings a week (), the same amount that Oliphant received for working at the State Library, but it allowed him to take any university course that did not conflict with his work for the department. He received his Bachelor of Science (BSc) degree in 1921 and then did honours the following year, supervised by Grant. Roy Burdon, who acted as head of the department when Grant went on sabbatical in 1925, worked with Oliphant to produce two papers in 1927 on the properties of mercury, "The Problem of the Surface Tension of Mercury and the Action of Aqueous Solutions on a Mercury Surface" and "Adsorption of Gases on the Surface of Mercury". Oliphant later recalled that Burdon taught him "the extraordinary exhilaration there was in even minor discoveries in the field of physics". Oliphant married Rosa Louise Wilbraham, who was also from Adelaide, on 23 May 1925. The two had known each other since they were teenagers. He made Rosa's wedding ring in the laboratory from a gold nugget (from the Coolgardie Goldfields) that his father had given him. Cavendish Laboratory In 1925, Oliphant heard a speech given by the New Zealand physicist Sir Ernest Rutherford, and he decided he wanted to work for him – an ambition that he fulfilled by earning a position at the Cavendish Laboratory at the University of Cambridge in 1927. He applied for an 1851 Exhibition Scholarship on the strength of the research he had done on mercury with Burdon. It came with a living allowance of £250 per annum (). When word came through that he had been awarded a fellowship, he wired Rutherford and Trinity College, Cambridge. Both accepted him. Rutherford's Cavendish Laboratory was carrying out some of the most advanced research into nuclear physics in the world at the time. Oliphant was invited to afternoon tea by Rutherford and Lady Rutherford. He soon met other researchers at the Cavendish Laboratory, including Patrick Blackett, Edward Bullard, James Chadwick, John Cockcroft, Charles Ellis, Peter Kapitza, Egon Bretscher, Philip Moon and Ernest Walton. There were two fellow Australians: Harrie Massey and John Keith Roberts. Oliphant would become especially close friends with Cockcroft. The laboratory had considerable talent but little money to spare, and