Marine chronometers, often considered precision instruments, proliferated in navigational practices during the nineteenth century. This paper examines their use in the hands of naval officers in the early-nineteenth century. It argues that both the instruments and their operators required careful management and regulation. In addition, officers learnt and adapted observatory practices relating to the process of data collection and management. Through these means, chronometric data was collected, organized, and reduced to negotiate accurate results.

This article maps out the lexical landscape of precision from the late seventeenth to the early eighteenth century and investigate the various meanings of precision, both as a word and a concept, within the Paris Observatory and beyond. It argues that precision was first an attribute of instruments supposed to produce numerical measurements, like clocks and divided circles or sectors attached to optical devices. Less often, precision was applied to observers, the handling of instruments, and observational methods, including mathematical corrections (...) applied to raw data. When all these aspects were combined the numerical result finally was also deemed to be precise. Moving to the debate about the shape of the Earth that shook the Academy of Sciences in the 1730s, it follows the way in which wider audiences were conveyed the various meanings of precision. Between the Cartesian resistance to the emergence of a professional science of precision and the pedagogical approach followed by the Newtonians such as Maupertuis, it argues that Cassini III embraced the professionalism of modern science, but did not feel that methodological precision was out of the reach of an educated public. While Maupertuis has seemed content with a discussion focusing on the precision of instruments and results, Cassini III set himself the hefty task of producing an accessible account of precision as a method of inquiry. (shrink)

Precision was not a quality expected from ordinary watches in the eighteenth century, which required specific maintenance to function correctly. The precautions to be taken to ensure the accuracy of pocket chronometers, whose going would influence navigation or the results of scientific activities, were even more vital. However, the remarkable attention that horological studies have devoted to the origins of chronometry has neglected these aspects. It has erroneously assumed that the success of chronometers was guaranteed by their innovative impact and (...) technological advancement. To illustrate the importance to examine the birth of chronometry from the point of view of manipulating technology and the user experience, my paper will discuss the case of the small series of pocket chronometers manufactured between 1782 and 1794 by the London workshop of the Swiss watchmaker Josiah Emery. The article shows that not all the users possessed the necessary technical knowledge nor training to handle and employ chronometers appropriately and that the instructions given by the artisan to his clients played a fundamental role. (shrink)

This paper explores discussions centred on the activities of the British Board of Longitude to consider the ways in which some men of science, instrument makers and others thought about questions of precision and accuracy, both in principle and in terms of what was possible in practice when making observations at sea. It considers firstly the terminology used in some eighteenth- and early nineteenth-century texts, highlighting the concept of exactness, which was more commonly used to describe one of the desirable (...) qualities of instruments and methods. It then looks at some of the discussions and debates in which the Board of Longitude was involved from the 1760s to think about different actors’ expectations of what levels of exactness might be either desirable or possible for day-to-day navigation. The focus is on the ability to make accurate shipboard observations and on the question of what degree of exactness might have been accepted as good enough for routine navigational purposes when at sea. (shrink)

This paper explores the various meanings of precision during the early modern period in Europe. In contrast with existing literature focused on assessing the precision of early instruments, this study delves into the intended significance of the term ‘precision’ as understood by historical figures such as J. Stöffler, P. Nunes or F. Mordente. By analysing a selection of instruments equipped with scales, both in their physical form and as they are described in instrument texts, several facets of precision emerge. Some (...) findings demonstrate that the precision of scales can be enhanced through corrections obtained from tables. In other cases, visual estimation is substituted with a method for obtaining values of multiple sexagesimal places. Furthermore, certain instruments designed to represent theoretical concepts achieve greater precision by incorporating the most intricate details of these notions. This investigation into lesser-known meanings of precision underscores the need of comprehensively exploring the concepts, the practices and the terminology surrounding precision that were in use over the fifteenth and sixteenth centuries. (shrink)

In 2017 a clock from the collection of the Mathematisch-Physikalischer Salon in Dresden was dismantled. This clock had been made around 1767 by Johann Gottfried Köhler (1745–1800), who was then in...

1. In June 1737, Jean Jacques Dortous de Mairan (1678–1771) informed Joseph-Nicolas Delisle (1688–1768) about the dispatch from Paris of six pendulum clocks and one seconds counter designed for the...

We explore the extent to which ancient Greek authors formulated concepts that approximate or encompass our modern notions of precision and accuracy. First, we focus on estimates and measurements of geographic features, astronomical times and positions, and weight. These raise further questions about whether the quantities reported were measured, estimated, or rounded. While ancient sources discuss the use of instruments, it is not always clear that the aim was to achieve what we would today regard as ‘precision’. Next, we briefly (...) consider round numbers, observing that they could carry symbolic meaning, while unrounded numbers could give an impression of hard-won achievement. Finally, we examine uses of the word akribeia. This is often translated as ‘precision’ or ‘exactness’, and Greek writers sometimes used akribeia to denote an ideal for their inquiries. A brief look at its uses by a number of Greek writers will on the one hand show the mismatch with our term ‘precision’, and on the other hand throw some light on the aims of Greek investigators. (shrink)

The instrumental character of Francis Bacon’s natural and experimental histories was often noted, but never fully investigated. In this paper I aim to reconstruct the theoretical and methodological background which supports this feature. I claim that we can read large parts of the second book of Bacon’s Novum organum as a guide to laboratory practices; and that it was read in this manner by some of Bacon’s seventeenth century followers. Key to this guide is Bacon’s theory of prerogative instances which, (...) in turn, provides the grounding for a whole theory of instruments of detection and instruments of measurement. I show, in particular, how Bacon suggested that such instruments can be used for ‘charting’ virtues and powers; a process in which instruments of detection can be transformed into instruments of measurement. I also show that Bacon’s views on instruments entail an elaborated conception of measurement which departs from the ethos of artisanal perfection. Instead of pursuing the ‘best results’, Bacon’s instrumental natural and experimental histories aim to offer a large enough corpus of correlations, estimates and calculations which, taken together, can represent more or less accurately changes and variations of natural virtues and powers. (shrink)

This paper examines the role of mathematical instrument makers in establishing a public culture of precision measurement in early-modern England. I argue that this culture was promoted through trials and demonstrations, in the context of which artisans held a privileged position. The trials described here cover land surveying, the measurement of magnetic variation, and standards of measurement for customs and excise. These trials were decisive moments in the ‘cultural biographies’ of precision instruments. I ask how it was that instrument makers (...) were able to assume positions of authority, and what this means for our understanding of the socio-material system of precision measurement in the early-modern period, and the contemporary rise of ‘experimental’ and ‘philosophical’ trials. Because practical mathematics was a self-consciously economic activity – motivated by trade, commerce, exploration and colonization – direct connections to natural philosophy are significant, a point explored in my conclusion. (shrink)

In the century between the creation of the first large, European astronomical observatory by Tycho Brahe in the 1580s and the national observatories of France and England in the 1660–1670s, astronomers constructed ever more sets of tables, derived from various geometrical and physical models, to compute planetary positions. But how were these tables to be evaluated? What level of precision or accuracy should be expected from mathematical astronomy? In 1644, the Stetin astronomer and calendar-maker Lorenz Eichstadt published a new set (...) of tables, mostly cobbled together from earlier tables, which include a running commentary on how his tables might be expected to match ‘observed’ planetary positions. His earlier works also often display a rhetoric of ‘exactitude’ and ‘error’. Eichstadt thus offers a case study of explicit discussions of ‘precision’ in mid-seventeenth astronomy. Although some tables could generate positions to arcseconds, Eichstadt argued that a regime of five arcminutes should be enough for most table users who were, presumably, computing horoscopes. (shrink)

This article discusses the ways in which nineteenth-century geodesists reflected on precision as an epistemic virtue in their measurement practice. Physical geodesy is often understood as a quintessential nineteenth-century precision science, stimulating advances in instrument making and statistics, and generating incredible quantities of data. Throughout most of the nineteenth century, geodesists indeed pursued their most prestigious research problem – the exact determination of the earth’s polar flattening – along those lines. Treating measurement errors as random, they assumed that remaining discordances (...) could be overcome by manufacturing better instruments and extending statistical analysis to a larger amount of data. In the second half of the nineteenth century, however, several German geodesists developed sophisticated methodological critiques of their discipline, in which they diagnosed a too-narrow focus on precision among their peers. On their account, geodesists urgently needed to identify and anticipate the causes of the remaining measurement errors that arose from the earth’s little understood interior constitution. While mostly overlooked in the literature, these critiques paved the way for many empirical successes in late nineteenth- and early twentieth-century geodesy, including the first convergent measurements of the earth’s polar flattening. (shrink)

In the 1720s two Jesuit astronomers working at the court of King João V of Portugal, in Lisbon, received several instruments produced by the best makers in London, Paris and Rome. With the crucial help of the Portuguese diplomatic network contacts with academies, savants and instrument makers were established, seeking technical advice and the best astronomical instruments available at the time. It was in this context that in April 1726 a set of Latin instructions accompanying pendulum clocks made by George (...) Graham were dispatched from London to Lisbon. These unpublished instructions are now preserved in the papers of Giovanni Battista Carbone, one of these Jesuit astronomers, offering a significant window into the procedures and technical details involved in the setting, operation and transport of Graham’s astronomical clocks. In this paper, I will not only discuss this important document in the framework of Graham’s contributions to astronomy and horology, but also in the perspective of the search for accuracy. (shrink)