John Joly

John Joly ( born 1 November 1857 in Bracknagh, County Offaly, Ireland, † December 8, 1933 in Dublin) was an Irish physicist and geologist who dealt with radioactivity and in medicine ( radiotherapy) and geological age determination anwandte. He is also known for his contributions to color photography and plant physiology.

Life

Joly began in 1876 to study engineering at Trinity College, Dublin, with the completion in 1882, where he also studied modern literature and other subjects. After graduation, he was Demonstrator in the Departments of Engineering and Physics Trinity College. In 1897 he was appointed as successor to William Johnson Sollas, Professor of Geology and Mineralogy at Trinity College, which he remained until his death.

In 1899, he proposed a method before, to determine the age of the earth from the sodium content of the oceans, from the idea that its concentration would increase steadily through erosion on land. He estimated the age of the earth then to 80 to 100 million years. In 1903, he suggested a better method to estimate the geological era from the radioactive decay of radium ( in a Nature article ). He has worked in this field with Ernest Rutherford and concluded from his studies in 1913, that the beginning of the Devonian dates back at least 400 million years. He also discussed uranium and other radioactive elements as a source of heat from the Earth's interior, for example, 1908 in the Presidential Address to the British Association at their meeting in Dublin (Uranium and Geology ).

He turned to the radioactivity in medicine after he had developed in 1914 a chemical method for the extraction of radium. From him came a method of cancer therapy with radium, which was introduced via a hollow needle into the body. On his initiative the Irish Radium Institute was founded and worked in cancer therapy with Dr. Steevens Hospital together in Dublin.

He developed various instruments such as a photometer, a device for measuring the melting point of minerals, a Calorimeter, a thermometer and a named after him process for color photography ( line grid method of Joly, 1894).

With his friend Henry Horatio Dixon (1869-1953), professor of biology at Trinity College, he developed in 1894 a cohesion theory of water and mineral transport in the xylem of plants.

In 1923 he received the Murchison Medal. He was a Fellow of the Royal Society, the Royal Medal he received in 1910. In 1911 he received the Boyle Medal of the Royal Dublin Society, which he was a member since 1881. In 1908 he was President of Section C of the British Association for the Advancement of Science. He was more honorary doctorates ( National University of Ireland, University of Cambridge, University of Michigan ). Even today Joly Memorial Lectures held at the University of Dublin.

1973 a crater on Mars was named after him.