"atom of electricity". In 1891, he proposed the term 'electron' to describe the fundamental unit of electrical charge, and his contributions to research in this area laid the foundations for the eventual discovery of the particle by J. J. Thomson in 1897. His scientific work was carried out in his spare time. A heliostat designed by Stoney is in the Science Museum Group collection. Stoney was elected a Fellow of the Royal Society in June 1861 on the basis of being the author of papers on "The Propagation of Waves", "On the Rings seen in Fibrous Specimens of Calc Spar", and Molecular Physics, published in the Transactions of the Royal Irish Academy, et cetera, Distinguished for his acquaintance with the science of Astronomy & General Physics. Stoney units Stoney proposed the first system of natural units in 1881. He realized that a fixed amount of charge was transferred per chemical bond affected during electrolysis, the elementary charge e, which could serve as a unit of charge, and that combined with other known universal constants, namely the speed of light c, the Newtonian constant of gravitation G and the Coulomb constant ke, a complete system of units could be derived. He showed how to derive units of mass, length, time and electric charge as base units. Like Stoney, Planck independently derived a system of natural units (of similar scale) some decades after him, using different constants of nature. Hermann Weyl made a notable attempt to construct a unified theory by associating a gravitational unit of charge with the Stoney length. Weyl's theory led to significant mathematical innovations but his theory is generally thought to lack physical significance. Family Stoney married his cousin, Margaret Sophia Stoney, by whom he had had two sons and three daughters. For most of his decades in Dublin, Stoney resided in the Dundrum, Dublin neighbourhood. The street that he lived on was later renamed Stoney Road in his memory. After Stoney died in London, his cremated ashes were buried in St. Nahi's Church in Dundrum. One of Stoney's sons, George Gerald Stoney FRS, was a scientist. His daughter Florence Stoney OBE was a radiologist while his daughter Edith is considered to be the first woman medical physicist. Stoney's most scientifically notable relative was his nephew, the Dublin-based physicist George Francis FitzGerald (1851–1901). His brother was the engineer Bindon Blood Stoney. Legacy Stoney received an honorary Doctorate of