and placed a zinc plate in a porous pot (a pot that had an inside and outside chamber for holding two different types of acid) in the centre. Using a single fluid cell he disposed of the porous pot and two different fluids. He was able to build a battery with just a single solution. While experimenting with batteries, Callan also built the world's largest battery at that time. To construct this battery, he joined together 577 individual batteries ("cells"), which used over 30 gallons of acid. Since instruments for measuring current or voltages had not yet been invented, Callan measured the strength of a battery by measuring how much weight his electromagnet could lift when powered by the battery. Using his giant battery, Callan's electromagnet lifted 2 tons. The Maynooth battery went into commercial production in London. Callan also discovered an early form of galvanisation to protect iron from rusting when he was experimenting on battery design, and he patented the idea. He died in 1864 and is buried in the cemetery in St. Patrick's College, Maynooth. Legacy The Callan Building on the north campus of NUI Maynooth, a university which was part of St Patrick's College until 1997, was named in his honour. In addition, Callan Hall in the south campus, was used through the 1990s for first year science lectures including experimental & mathematical physics, chemistry and biology. The Nicholas Callan Memorial Prize is an annual prize awarded to the best final year student in Experimental Physics. Publications Electricity and Galvanism (introductory textbook), 1832 See also List of Roman Catholic scientist-clerics References Notes O'Hara, James G.Callan, Nicholas Joseph (1799–1864), Oxford Dictionary of National Biography, Oxford University Press, 2004 Biography at corrosion-doctors.org External links Nicholas Callan at the Science Museum, Maynooth (his translations) 1799 births 1864 deaths Irish inventors Irish physicists Academics of St Patrick's College, Maynooth Alumni of St Patrick's College, Maynooth 19th-century Irish Roman Catholic priests People from County Louth Catholic clergy scientists Burials at Maynooth College Cemetery