In 1922, he joined the Department of Biochemistry at Cambridge, where he was directed to research
haemoglobin. He published a number of papers on haemoglobin, and in 1926 he began to work with
David Keilin on the
haem containing
protein cytochrome c. In 1932, he commenced work on plant biochemistry, focusing on photosynthesis and the oxygen evolution of
chloroplasts, leading to the discovery of the 'Hill reaction'. From 1943, Hill's work was funded by the
Agricultural Research Council (ARC), although he continued to work in the Cambridge Biochemistry Department. Hill continued to receive most of his recognition for his earlier work on photosynthesis, and beginning in the late 1950s, his work concentrated on the energetics of photosynthesis. In collaboration with Fay Bendall, he made his second great contribution to photosynthesis research with the discovery of the 'Z scheme' of electron transport. Hill retired from the ARC in 1966, although his research at Cambridge continued until his death in 1991. In his later years Hill worked on the issue of the application of the
second law of thermodynamics to photosynthesis. He was an expert on
natural dyes and cultivated plants such as madder and woad. He painted watercolours using pigments he himself extracted. In the 1920s, he developed a fish-eye camera and used it to take stereoscopic whole-sky images, recording cloud patterns in three dimensions. ==Awards and honours==