In this article, I discuss manuscript material written by Petrus van Musschenbroek (1692–1761) related to his first experiments with the Leiden jar. Despite the importance of the discovery of the Leiden jar for the history of electricity and the questions that still surround its discovery, a detailed treatment of this manuscript material is lacking in the literature. The main aim of this paper is to provide an outline of the manuscript material and to contextualize van Musschenbroek’s first experiments with the Leiden jar. I show how the experiment fits within his research program on electricity and I discuss van Musschenbroek’s initial reactions to and analysis of the phenomenon. Before doing so, I first provide a short overview of the treatment of the early history of the Leiden jar in the secondary literature. After that, I discuss van Musschenbroek’s treatment of the topic of electricity in the textbooks he published in the years before the discovery of the device. Van Musschenbroek repeatedly emphasized that not enough experimental results were available for an informed theoretical treatment of the phenomenon of electricity to be possible. I then turn to the manuscript material, where I give a general description of the contents of the manuscript and van Musschenbroek’s experimental practice. The manuscript material further confirms recent work on the Leiden jar by Silva and Heering, and provides new insights into the way van Musschenbroek himself reacted to the discovery.

In this article, we discuss the development of the concept of a 'law' (of nature) in the work of the Dutch natural philosopher and experimenter Petrus van Musschenbroek (1692-1761). Since Van Musschenbroek is commonly described as one of the first 'Newtonians' on the Continent in the secondary literature, we focus more specifically on its relation to Newton's views on this issue. Although he was certainly indebted to Newton for his thinking on laws (of nature), Van Musschenbroek's views can be seen to diverge from Newton's on crucial points. We show, moreover, how his thinking on laws of nature was shaped by both international and local factors. We start with a brief discussion of Newton's concept of 'laws of nature' in order to set the stage for Van Musschenbroek's. We then document the development of Van Musschenbroek's views on laws of nature in chronological order. We demonstrate how his thinking on laws of nature was tied to institutional, theological and scientific factors. We conclude by pointing to the broader significance of this case study for our understanding of the development of the concept 'law of nature' during the eighteenth century.

The Dutch Republic played an important role in the dissemination of Newton’s philosophy. There, it found its earliest proponents, who were instrumental in the spread of Newton’s ideas on the Continent. One of these figures was Petrus van Musschenbroek (1692-1761), who took up professorships at the universities of Duisburg, Utrecht, and Leiden. In a letter to Newton written at the beginning of his academic career, van Musschenbroek explicitly stated that it was his aim to spread the ‘Newtonian philosophy’ in the university, and from there to the rest of Dutch society. In this article, I focus on van Musschenbroek’s activities in the context of his professorship at different universities in the Dutch Republic. I analyse the way van Musschenbroek presents Newton and his philosophy in his academic orations and the prefaces to the different editions of his textbook. I argue that van Musschenbroek implicitly uses a certain view on the institution of the university and its tasks as a leverage in his defence of ‘(Newtonian) experimental philosophy’ and his attack on the existing tradition of Cartesian philosophy in the university. I also show how van Musschenbroek was not consistent in presenting his philosophy as specifically ‘Newtonian’, and increasingly emphasised that he should not be seen as a ‘follower’ of Newton, but rather as an impartial ‘experimental philosopher’. This shift, however, can be seen as motivated by the same rhetorical strategy used by van Musschenbroek in his earlier defence of ‘Newtonian’ experimental philosophy.

This chapter compares Robert Hooke’s views on the use of writing as an external memory with contemporary notions of extended and distributed cognition. The aim is not to portray Hooke as a proponent of these views avant la lettre, but to highlight certain interesting structural similarities and differences. Hooke believed that cognition could be externalised through the use of an external ‘repository’. In this case, cognition takes place through the manipulation of written material. This externalisation of memory makes it possible for other people to access, supplement, and organise the same ‘repository’, which allows for a cognitive division of labour. It is further shown how the Royal Society, of which Hooke was a member, is presented by Thomas Sprat as an enterprise aimed precisely at this kind of cognitive division of labour. The chapter concludes with a concrete example of an ‘external repository’ designed by Hooke, analysing the way it puts into practice Hooke’s ideas on individually and socially extended cognition.