Irish ‘Rock Stars’ Patrick Wyse Jackson, Trinity College Dublin, continues his series John Joly (1857-1933) Colour image of a parrot taken by Joly using his ‘Joly Method’. This stuffed bird is now in the Department of assistantships in engineering and then Geology, TCD. in physics before obtaining the Chair Dublin Society in which he calculated the of Geology and Mineralogy. In his early Earth to be 100 million years old, and career he can be regarded as being soon the earlier estimate evaporated an inventor and physicist. His steam away. Joly derived his global time-span calorimeter allowed for the measurement from an estimate of the volume of sodium of the specific heat of minerals and in the oceans that he divided by the rate this piece of equipment later played an at which it was carried into the oceans by important role in the development of the rivers. It is not surprising that he turned kinetic theory of gases. to the sea for his inspiration as he was Joly had the ability to focus his mind a notable yachtsman, who was also a on a wide variety of subjects outside Commissioner for Irish Lights for whom his immediate academic discipline, he undertook an annual inspection of and together with his life-long friend lighthouses. He was a pioneer in the the botanist Henry Horatio Dixon, he field of radioactivity and its connections explained the mechanism of the ‘ascent to geology. In 1907 he demonstrated that John Joly: an early photograph of sap’ or transportation of water in pleochroic halos found in biotite in some (Courtesy of the late Ted Nevill). plants. They showed that this was driven granites were formed as a result of the by a pressure gradient set up in plant decay of radioactive zircon crystals. He When the Russian scientist Dmitri vessels through the loss of water from established the Irish Radium Institute Mendeleyev developed the idea of the the surface of leaves by transpiration. in 1914 that exploited the medical Periodic Table of the elements over In the late 1890s he invented a system advantages of radium. a two-week period early in 1869 it is of colour photography called the ‘Dublin Joly was probably the most brilliant unlikely that he would have predicted method’ or ‘Joly Method’ in which he Irish scientist of his generation. He the nationalistic fervour that marked the produced colour images by lining up a was elected a Fellow of the Royal discovery and naming of elements in glass plate marked with thin lines of the Society before being admitted to the the late 1800s. Gallium (for France) in primary colours with a negative. Many of Irish equivalent, and received medals 1875, Germaniumin 1886 and Polonium his images are still-life compositions of from the Royal Society, the Royal Dublin in 1898 were so named. In 1922 John plants but also include a stuffed parrot. Society and the Geological Society. Joly of Trinity College, Dublin named He established a business on Brunswick Hibernium, a new radioactive element he Street (now Pearse Street), Dublin to He died in Dublin on 8th December 1933 had discovered in granite. Unfortunately exploit his invention but it failed, as it and is buried in Mount Jerome Cemetery. for both Joly and Ireland it was later proved difficult to produce colour prints Forty years later he had a crater on Mars discovered that the new element was in from his glass slides. Until the advent named for him, which was appropriate fact Samarium that had been isolated of digital methods Joly’s invention was given his research on the nature and over sixty years earlier. essentially the scheme used for colour origin of Martian Canals. photography. Joly was born on 1st November 1857 Patrick N. Wyse Jackson, in Hollywood House (the Rectory), After his professorial appointment in Trinity College, Dublin Bracknagh, County Offaly, the third and 1897 he shifted his focus to matters more youngest son of John Plunket Joly and geological, but he cannot be regarded Julia AnnaMaria Georgina née Comtesse as a field geologist. To my knowledge de Lusi, and this year we are celebrating he never drew a geological map, nor did the sesquicentenary of his birth. He he accumulate large collections through was a distinctive man who sported a his own collecting. However he is now bushy moustache and wore pince-nez remembered in geological circles for his perched on his nose. By all accounts considerable and important research he was highly popular with his students, into geochronology and in the fledgling and very generous to colleagues with his subject of geodynamics and tectonics. time and expertise. Towards the end of the nineteenth century Educated at the Rathmines School in William Thomson (later Lord Kelvin) Dublin, and later at Trinity where he argued that the Earth was between 24 studied classics and modern literature and 40 million years old. However in and later engineering. He was to remain 1899,Joly published an influential paper Pleochroic halos in Leinster Granite there for the rest of his life, holding in the Scientific Transactions of the Royal from Co. Carlow. Issue 2 11.