In 1906-1907, Henri Poincaré lectured on “The Limits of Newton's Law” at the Paris Faculty of Sciences, from the Chair of Celestial Mechanics he had held since the death of Félix Tisserand in 1896. Poincaré set out to present and clarify the aporias encountered by Newton's law of universal gravitation, initially in the domain of astronomy, and then in electron dynamics. In July, 1905, Poincaré had proposed to extend the principle of relativity to all laws of physics, and his lectures outlined a relativistic version of the law of gravitation. The recent rediscovery of detailed student notes of Poincaré's lectures, and the discovery of Poincaré's own lecture notes have given rise to the first critical edition of his lectures. Based in part on the latter edition, I propose to broaden the context of discovery of Poincaré’s relativity, centered squarely up to now on electron theory, to include early twentieth-century research in celestial mechanics and astrophysics.

When Henri Poincaré discovered a new, pear-shaped equilibrium figure of homogeneous rotating fluid masses in 1885, he observed that evolution of this figure could result in fission. A few years earlier, G. H. Darwin argued that the Earth-Moon system evolved via tidal forces from a single rotating fluid mass. When the first spectroscopic binary stars were observed in 1889, the Poincaré-Darwin fission theory became a candidate for the origin of close binaries, and by 1901, following the discovery of hundreds of variable stars (including many binary systems), and the successful modeling by G. W. Myers of light curves of variable stars by eclipsing ellipsoids in Keplerian orbit, it was accepted as the most persuasive account by leading astronomers. An extension of fission theory to rotating gaseous masses was thought to explain not only the origin of binary stars, but also, in part, the origin of the solar system, and that of the Milky Way. My talk discusses the appeal and challenges of fission theory in the context of research in stellar evolution and cosmogony, from the early 1890s to 1924.

On 2 August 1710, Maria Margaretha Kirch, née Winckelmann (1670–1720), widow of the astronomer Gottfried Kirch (1639–1710), submitted a petition to the Royal Prussian Society of Sciences. She sought permission to make calendars for this institution and to continue astronomical observations at the Royal Observatory. On 25 November 1711, she took the next step: she presented her case to the King. In early 1712, the council of the Royal Prussian Society of Sciences made it clear that she should cease further efforts. Based on my research conducted in the Archive of the Berlin-Brandenburg Academy of Sciences and Humanities, I will examine the reasons behind her rejection. Through the analysis of the documentation of the Society of Sciences in Berlin – focusing on its history during the early 1710s, its financial challenges, and the selection process for astronomers and astronomical observers – I will argue that her rejection was not rooted in gender bias, but rather resulted from unique circumstances.

The 1874 United States expedition to the Chatham Islands for the observation of the Transit of Venus was the beginning of bilateral science between the U.S and New Zealand, as part of the multi-national observation programme. In preparation for the transit, instructions were sent from Lord Kimberley of the Foreign Office to Governor Fergusson for the New Zealand colony to provide logistical support and assistance for a U.S expedition to New Zealand sovereign territory. Two U.S expeditions set out for New Zealand, one based in Queenstown, one based in the Chatham Islands. The Southern Hemisphere teams set off from New York, with the Chatham Islands team arriving on the 19th October 1874 and staying on the Chathams until the 5th January 1875. Unfortunately, the weather on the day of the Transit, 9th December 1874, was cloudy, so only limited observations could be undertaken. This paper will focus on both the wider context of multilateral science in observing the Transit, as well as the history of the Chatham Islands expedition, expedition members, their time on island, scientific output, and photographic record of the expedition. We also will discuss the significance of 1874 marking the first bilateral scientific collaboration between both nations.