James Croll and 1876: an exceptional year for a ‘singularly modest man’

ABSTRACT James Croll left school at the age of 13 years, yet while a janitor in Glasgow he published a landmark paper on astronomically-related climate change, claimed as ‘the most important discovery in paleoclimatology’, and which brought him to the attention of Charles Darwin, William Thomson and John Tyndall, amongst others. By 1867 he was persuaded to become Secretary and Accountant of the newly established Geological Survey of Scotland in Edinburgh, and a year after the appearance of his keynote volume Climate and time in 1875, he was lauded with an honorary doctorate from Scotland's oldest university, Fellowship of the Royal Society of London and Honorary Membership of the New York Academy of Sciences. Using a range of archival and published sources, this paper explores aspects of his ‘journey’ and the background to the award of these major accolades. It also discusses why he never became a Fellow of his national academy, the Royal Society of Edinburgh. In the world of 19th-Century science, Croll was not unusual in being both an autodidact and of humble origins, nor was he lacking in support for his endeavours. It is possible that a combination of Croll's modesty and innovative genius fostered advancement, though this did not hinder a willingness to engage in vigorous argument.

Joule, Mayer, and Others: A Decade-and-a-Half-Long Debate over Priority in the Discovery of the Mechanical Equivalent of Heat

This article reviews the history of a debate over priority in the discovery of the mechanical equivalent of heat that was centered around J. P. Joule and J. R. von Mayer. The following two stages may be distinguished in this debate. During the first stage, those involved in it were Joule and Mayer themselves. While Mayer presented a numerical value for the mechanical equivalent of heat, which was based on the data from Gay-Lussac’s experiment, Joule determined the value of this coefficient in his own experiment although he did it later than Mayer (actually, Joule was unaware of Gay-Lussac’s experiment). This article shows that, in the end, Joule and William Thomson, who also participated in the debate, recognized (even though formally and with reservations) Mayer’s priority. During the second stage of the debate, its participants were British scientists who supported Mayer or Joule. Thus, Mayer’s priority was supported by Professor J. Tyndall of the Royal Institution in London and it was he who initiated the resumption of the discussion. Joule’s priority was advocated by Professor W. Thomson of the University of Glasgow and Professor P. Tait of the University of Edinburgh. It is noted that a personal animosity between Tyndall and Tait, as well as Tyndall’s competitive attitude towards Thomson, had a significant impact on the tone of the debate, and the examples of Tait’s provocative remarks and Tyndall’s reactions are provided. Joule’s involvement during the second stage of the debate that was mostly limited to private correspondence between himself, Tait, Thomson, and Tyndall, is discussed. Over the time elapsed after the first stage of the debate, the level of rejection of Mayer’s arguments by the scientific community had decreased significantly. The awarding of the Royal Society’s Copley Medal to Joule (1870) and Mayer (1871), both of them nominated by Tyndall, came as a symbolic conclusion of the debate.

The Gibbs-Thomson Equation

The external surface of a material has an atomic or molecular structure that is different from the bulk material. So does any internal interface within a material. Because of this, the energy of a material or any grain or particle within it increases with the curvature of its bounding surface, as described by the Gibbs-Thomson equation. This chapter explains how surfaces control the nucleation of new phases during reactions such as solidification and precipitation, the coarsening and growth of particles during heat treatment, the equilibrium shape of crystals, and the surface adsorption and segregation of solutes and impurities. The Gibbs-Thomson was predated by a number of related equations; it is not clear whether it is named after J. J. Thomson or William Thomson (Lord Kelvin); and it was not put into its current usual form until after Gibbs’, Thomson’s and Kelvin’s time. J. J. Thomson was the third Cavendish Professor of Physics at Cambridge University. He discovered the electron, which had a profound impact on the world, notably via Thomas Edison’s invention of the light bulb, and subsequent building of the world’s first electricity distribution network. William Thomson was Professor of Natural Philosophy at Glasgow University. He made major scientific developments, notably in thermodynamics, and he helped build the first trans-Atlantic undersea telegraph. Because of his scientific pre-eminence, the absolute unit of temperature, the degree Kelvin, is named after him.