(1999). A Longitude Timekeeper by Isaac Thuret with the Balance Spring Invented by Christiaan Huygens. Annals of Science: Vol. 56, No. 4, pp. 379-394.

This article surveys surviving evidence for the determination of geographic longitude in Latin Europe in the period between 1100 and 1300. Special consideration is given to the different types of sources that preserve longitude estimates as well as to the techniques that were used in establishing them. While the method of inferring longitude differences from eclipse times was evidently in use as early as the mid-twelfth century, it remains doubtful that it can account for most of the (...) preserved longitudes. An analysis of 89 different estimates for 30 European cities indicates a high degree of accuracy among the longitudes of English cities and a conspicuous displacement eastward (by 5°–7;30°) shared by most longitudes of cities in Italy and France. In both cases, the data suggest a high level of interdependence between estimates for different cities in the same geographic region, although the means by which these estimates were arrived at remain insufficiently known. (shrink)

(1984). Degrees of longitude and the earth's shape: The diffusion of a scientific idea in Paris in the 1730s. Annals of Science: Vol. 41, No. 2, pp. 151-158.

ArgumentThis article examines advertisements for potential solutions to the problem of longitude during the year following the announcement of the maximum £20,000 reward in the summer of 1714. While there have been many studies of the race to determine longitude, advertisements have not received close scrutiny. Little attention has been paid to the commoditization of longitude in the marketplace of public science sold within London's public sphere. Although books and lecture series dominated public science in eighteenth-century England, (...) longitude ads are a unique example of this phenomenon. Unlike lecturers or publishers of natural philosophical tracts who sought audiences for demonstrations or readers for books which contained accounts of nature that were not open to debate, longitude seekers were doing something different. Those who attempted to solve the problem of longitude and advertised their plans to the public sought out witnesses to validate and confirm the effectiveness of their experiments or instruments. In other words, the public sphere became the crucible of judgment for schemes of longitude. (shrink)

Ibn al-Bann1321) is the author of one of the four extant of the unfinished zq (fl. Tunis and Marrakesh ca. 1193j accessible for the computation of planetary longitudes. The present paper studies some modifications of the structure of the tables the purpose of which is to make calculations easier. The tables of the planetary and lunar equations of the centre are ' appears as a clever adapter, who displays a clear ingenuity allowing him to introduce formal modifications which give his (...) work an appearance of novelty which does not correspond to reality. (shrink)

In the 1760s, the international debate on the solution to determining longitude at sea is at its acme. Two solutions emerge, the mechanical and the astronomical ones. The Portuguese mathematician and astronomer José Monteiro da Rocha (1734–1819) is well aware of that debate. For him, Harrison’s No. 4 marine timekeeper cannot be seen as a solution. The desirable solution could only be astronomical. In a manuscript from c. 1765, which unfortunately he fails to publish, Monteiro da Rocha is very (...) critical of Lacaille's lunar-distance method (1759) and proposes another one. In this paper, we intend to analyse Monteiro da Rocha’s criticisms and proposals, trying to understand how this manuscript fits into the international longitude debate and the Portuguese scientific scenario at the time. Concurrently, we will re-examine the classical historiography around the English vs. French priority proposal of the lunar-distance method, purging it from its mythologies to shift it towards a more open, less linear history. (shrink)

The difference in longitude between the observatories of Paris and Greenwich was long of fundamental importance to geodesy, navigation and timekeeping. Measured many times and by many different means since the seventeenth century, the preferred method of the later nineteenth and early twentieth centuries made use of the electric telegraph. I describe here for the first time the four Paris–Greenwich telegraphic longitude determinations made between 1854 and 1902. Despite contemporary faith in the new technique, the first was soon (...) found to be inaccurate; the second was a failure, ending in Anglo-French dispute over whose result was to be trusted; the third failed in exactly the same way; and when eventually the fourth was presented as a success, the evidence for that success was far from clear-cut. I use this as a case study in precision measurement, showing how mutual grounding between different measurement techniques, in the search for agreement between them, was an important force for change and improvement. I also show that better precision had more to do with the gradually improving methods of astronomical time determination than with the singular innovation of the telegraph, thus emphasizing the importance of what have been described as ‘observatory techniques’ to nineteenth-century practices of precision measurement. (shrink)

Summary John Harrison (1693–1776) is regarded as the father of chronometry. During his lifetime, he relentlessly pursued one of humankind's greatest and oldest challenges—that of finding the longitude at sea. In succeeding (according to the rules dictated by an Act of Parliament), he bequeathed to humankind the most accurate portable timekeeper the world had ever seen. It is a remarkable fact that his timekeeper, known today as H4, remains more accurate than the majority of expensive mechanical wristwatches manufactured today. (...) Such accuracy required novel approaches to address the various difficulties that befall all mechanical watches, and Harrison overcame many of these with his own innovations. The reduction or elimination of friction is one such problem with clocks and watches, and from an early age Harrison demonstrated his mastery in this subject. This is typified by his choice of woods in his early clocks, and in later clocks by his ‘grasshopper’ escapement. In the 1750s, Harrison's attention switched from clocks to watches, necessitating a hardwearing, low friction material to be found for the pallets in the escapement of his timekeepers. He found these properties in diamond, and in utilizing this to great effect in H4's escapement, he became one of the first people to use diamond as a high-tech material. This paper describes a scientific investigation into the diamond pallets of H4 using Raman microscopy, X-ray diffraction and optical microscopy, to elucidate why diamond was used rather than a more conventional jewel such as ruby, and to gain some insight into how Harrison might have achieved their unconventional morphology. From the evidence presented here, together with evidence collected from primary sources, it is shown that his use of diamond as a hard, low friction material was nothing other than extraordinary, and should be regarded in the same high esteem as his other technological gifts to the world. (shrink)

이 논문은 俛宇(郭鍾錫, 1846-1919)의 사단칠정설을 ‘氣의 經緯說’에서 주목하여 조명하고 있다. 논문에 따르면, 면우의 경위설은 ‘理自發’과 ‘性發爲情’을 사단과 칠정에 고루 적용하면서도 四七양자를 구별하는 논리적 장치였다. 그는 이 이론에 입각하여 사단과 칠정의 의미에 대해 새로운 이해를 제시하였고 나아가 도덕감정 이론에서 의미 있는 진전을 보여주었다고 이 논문은 주장한다. 이 논문은 먼저 農巖의 경위설에 대한 면우의 비판과 계승을 살펴보고 그 의의를 분석한다. 면우에 따르면, 농암의 이론은 성발위정에 위배될 뿐 아니라 칠정의 도덕적 가능성을 간과하는 것이었다. 그래서 그는 새로운 경위설을 제시하여 그 오류들을 수정하고 사단칠정의 구조를 (...) 재정립하였다. 이어서 이 논문은 면우가 四端不中節의 문제를 해결해가는 과정과 그 의의를 살펴보고 있다. 면우는 사단의 무오류성을 적극 천명하고 측은지심의 무한 확장을 주장하였다. 마지막으로 이 논문은 그가 사단의 완전성에 대한 믿음에 기초하여 達道의 七情을 강조하고 칠정의 도덕적 가능성을 천명한 것을 고찰한다. 그리고 면우의 사단칠정론이 공공의 감정론으로 귀결된다는 점에 주목한다. (shrink)

This summer, I met Stephan Van Dam, a mapmaker and publisher so well known for his innovative work that twenty‐six of his maps are in the permanent collection of the Museum of Modern Art in New York. We talked about our work, and he connected bioethics to mapping. “After all, ethics is action,” he said. I've thought about that since because I found it a great description for bioethics and my role in it. Being concerned with how things ought to (...) be requires a map of how they are and where we want to go. As director of public affairs and communications at The Hastings Center, my job is to help put the normative and empirical research of our scholars into action via policy‐makers, journalists, and the public—to place it on the map. (shrink)

When Christiaan Huygens prepared the 1686/1687 expedition to the Cape of Good Hope on which his pendulum clocks were to be tested for their usefulness in measuring longitude at sea, he also gave instructions to Thomas Helder to perform experiments with the seconds-pendulum. This was prompted by Jean Richer's 1672 finding that a seconds-pendulum is 1 1/4 lines shorter in Cayenne than in Paris. Unfortunately, Helder died on the voy¬age, and no data from the seconds-pendulum ever reached Huygens. He (...) nevertheless did receive data from his clocks on the return-voyage from the Cape of Good Hope to Texel. When he first calculated the ship's course according to these data, it appeared to have gone straight through Ireland. He then tried introducing a correction to the data, based on an idea he had previously entertained as a possible explanation of Richer's finding: he corrected the observed time to com¬pen¬sate for a reduction in the effect of gravity from the Poles to the Equator resulting purely from the Earth's rotation. His newly calculated course convinced him that this rotational effect is the sole source of any variations in gravity with latitude. This paper examines Huygens's correc¬tions to the data and his reasoning from the new course to the conclusion that nothing else causes a variation in gravity. In the process, we show that Huygens had cogent empirical reasons to reject Isaac Newton's theory of universal gravity, which predicted a some¬what larger variation in gravity. (shrink)

En 1885, le Bureau des longitudes se voit contraint d’adapter les éphémérides de la Connaissance des temps aux besoins des navigateurs. En procédant à un audit sur les éphémérides en usage dans les ports, le Bureau redécouvre que depuis 1836 sont publiées à Saint-Brieuc des Éphémérides maritimes,véritables extraits de la CDT. Nous avons ainsi identifié une affaire de contrefaçon d’éphémérides nautiques. Les pièces de son jugement par un tribunal rennais posent la question cruciale de la propriété intellectuelle des calculs astronomiques. (...) Au-delà de cette affaire concernant des imprimeurs-libraires briochins et parisiens, nous interrogeons aussi l’insuffisance de la réponse apportée par le Bureau des longitudes aux demandes répétées de simplification des éphémérides à destination des marins. (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)

Population counts and longitude and latitude coordinates were estimated for the 50 largest cities in the United States by computational linguistic techniques and by human participants. The mathematical technique Latent Semantic Analysis applied to newspaper texts produced similarity ratings between the 50 cities that allowed for a multidimensional scaling (MDS) of these cities. MDS coordinates correlated with the actual longitude and latitude of these cities, showing that cities that are located together share similar semantic contexts. This finding was (...) replicated using a first‐order co‐occurrence algorithm. The computational estimates of geographical location as well as population were akin to human estimates. These findings show that language encodes geographical information that language users in turn may use in their understanding of language and the world. (shrink)

In his comprehensive survey of the work of William Herschel, published in the Annuaire du Bureau des Longitudes for 1842, Dominique Arago argued that the life of the great astronomer ‘had the rare privilege of forming an epoch in an extended branch of astronomy’. Arago also noted, however, that Herschel's ideas were often taken as ‘the conceptions of a madman’, even if they were subsequently accepted. This fact, commented Arago, ‘seems to me one that deserves to appear in the history (...) of science’. From the time Herschel published his first paper in the Philosophical transactions in 1781, he was subjected to the suggestion of lunacy. His patron and friend William Watson, told him that after his claims for the extraordinary power of his telescopes, ‘your prognosis that some would think you fit for Bedlam has been verified’. On learning of Herschel's supremely accurate new micrometer, the astronomer Alexander Aubert exclaimed to Herschel that ‘we would go to Bedlam together’: Aubert wrote to Herschel in January 1782 that he should ‘mind not a few jealous barking puppies: a little time will clear up the matter, and if it lays in my power you would not be sent to Bedlam alone, for I incline much to be of the party’. (shrink)

Ibn al-Zarqālluh (al-Andalus, d. 1100) introduced a new inequality in the longitudinal motion of the Moon into Ptolemy’s lunar model with the amplitude of 24′, which periodically changes in terms of a sine function with the distance in longitude between the mean Moon and the solar apogee as the variable. It can be shown that the discovery had its roots in his examination of the discrepancies between the times of the lunar eclipses he obtained from the data of his (...) eclipse observations over a 37-year period in the latter part of the eleventh century and the predictions made on the basis of the lunar theories in the Mumta $$\textit{\d{h}}$$ an zīj (Baghdad, ca. 830) and al-Battānī’s zīj (Raqqa, d. 929), which were available to him at the time. What Ibn al-Zarqālluh found is, in fact, a special case of the annual equation of the Moon, which is applicable in the oppositions and, thus, in the lunar eclipses. The inequality was discovered independently by Tycho Brahe (d. 1601) and Johannes Kepler (d. 1630). As Ibn Yūnus (d. 1009) reports in his $$\textit{\d{H}}$$ ākimī zīj, Ibn al-Zarqālluh’s medieval Middle Eastern predecessors, the Persian astronomers Māhānī (d. ca. 880) and Nayrīzī (d. 922) as well as ‘Alī b. Amājūr (fl. ca. 920), were already acquainted with the problem of the eclipse timing errors, but it had remained unresolved until Ibn Yūnus provided a provisional, and incorrect, solution by reducing the size of the lunar epicycle. As we argue, the diverse ways to tackle the same problem stem from two different methodologies in astronomical reasoning in the traditions developed separately in the Eastern and Western regions of the medieval Islamic domain. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Graffiti and Colonial Unknowing:A Comment on Mishuana Goeman's "Caring for Landscapes of Justice in Perilous Settler Environments"Anna Cookin "caring for landscapes of justice in Perilous Settler Environments," Dr. Goeman shows how the NDN Collective's initiatives, Chemehuevi photographer Cara Romero's Tongvaland project, and the works of Gabrieliño Tongva artist Mercedes Dorame "exemplify communities of care" that work toward "the unmapping of settler terrains" ("Caring for Landscapes" 51). Her address highlights (...) how these cartographic art productions are processes of (re)mapping that challenge colonial spatialities. Drawing on Michi Saagig Nishnaabeg scholar Leanne Betasamosake Simpson's poem "i am graffiti," Goeman frames these art works as Indigenous graffiti, insofar as they are everyday acts of resurgence1 that resist erasure and enact rematriation.My comments aim to articulate how Romero's and Dorame's works both reveal and disrupt a colonial unknowing by showing the cracks of settler colonial spatiality. I take Goeman's address to illustrate that the changing of minds and unsettling of settler identity will not occur through argumentation, facts, and figures alone, but rather through aesthetic and cartographic practices that "provide a way of seeing Indigenous futurities and relationalities" ("Caring for Landscapes" 52).Maps as Tools of Settler ColonialismIn order to highlight how these art practices enact a kind of (re)mapping that breaks through the veneer of colonial permanence, we first need to consider the way mapping transforms land into property in the service of Indigenous erasure and land dispossession. In her address, Goeman offers a short history of what is now called Los Angeles through the lens of dispossession that occurs through "international claiming of property and burgeoning US property law" ("Caring for Landscapes" 53). Tovaangar was divided into Spanish (and [End Page 64] then Mexican) land grants that, after 1846, were "registered under the US as property" (Goeman, "Caring for Landscapes" 53; emphasis added). The Land Act of 1851 "established the domestication of the California landscape under US governance" by legitimating existing Mexican land rights and mapping out territory yet "unclaimed" ("Caring for Landscapes" 54). The mapping of this so-called "unclaimed" territory propelled a violent erasure of California Indians by "establishing new and ongoing commerce centers" ("Caring for Landscapes" 53). Land was transferred into property—as a thing owned—without "the consent of those who … lived on the land since time immemorial, following the settler structure of passing land between Christian nations" ("Caring for Landscapes" 53). By showing how property rights legitimate conquest and violence, Goeman illustrates how mapping has been (and continues to be) an "essential settler-colonial tool to domesticate land in Southern California and propel development" ("Caring for Landscapes" 54). While she demonstrates how the mapping of Tovaangar using 493 hand-drawn Diseños maps served to sever Indigenous communities (and their relationships with land, such as the Gabrieliño Tongva with the San Gabriel Mountains), she emphasizes that this is an ongoing process that has not been left in a distant past. Newer maps that may seem more objective and scientific with "better models of scale or a more realist representation" remain, at their core, maps of dispossession ("Caring for Landscapes" 54).The very desire to objectively determine location by assigning latitude and longitude reveals a colonial spatiality, which "territorialize[s] the physical landscape by manufacturing categories and separating land from people" and conceives of space in terms of property logics (Goeman, "[Re]Mapping Indigenous Presence" 296). In addition to Indigenous land dispossession, this colonial spatiality rejects relationality by creating dualist boundaries between human and non-human, in which land is the raw material for human development and the creation of culture. Cherokee philosopher Brian Burkhart speaks of relationality in terms of locality, which he defines as "being-fromthe-land, knowing-from-the-land, and meaning-from-the-land" (Indigenizing Philosophy xvii). The severing of locality can be understood in terms of the transformation of land as relative to inert matter to be acted upon. Mapping serves as a tool of settler colonial erasure insofar as it delocalizes "land as the relational ground of kinship" into "land as a mere object that only has meaning or value in relation to people" ("Indigenizing Philosophy... (shrink)

This paper is a technical study of the systematic observations and computations made by Muḥyī al-Dīn al-Maghribī (d. 1283) at the Maragha observatory (north-western Iran, c. 1259–1320) in order to newly determine the parameters of the Ptolemaic lunar model, as explained in his Talkhīṣ al-majisṭī, “Compendium of the Almagest.” He used three lunar eclipses on March 7, 1262, April 7, 1270, and January 24, 1274, in order to measure the lunar epicycle radius and mean motions; an observation on April 20, (...) 1264, to determine the lunar eccentricity; an observation on August 29, 1264, to test the model; and another on March 15, 1262, for measuring the lunar parallax. In the second period of activity at the Maragha observatory, Shams al-Dīn Muḥammad al-Wābkanawī (c. 1254–1320) adopted all of al-Maghribī’s parameter values in his Zīj, but decreased his value for the mean longitude of the moon at epoch by 0;13,11∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{\circ }$$\end{document}. By comparing the times of the new moons and lunar eclipses in the period of 1270–1320 as computed from the astronomical tables of the Maragha tradition with the true modern ones, it is argued that this correction was very probably the result of actual observations. (shrink)

SummaryThe celebrated Swedish natural philosopher and visionary theologian Emanuel Swedenborg (1688–1772) devoted major efforts to the establishment of a reliable method for the determination of longitude at sea. He first formulated a method, based on the astronomical observation of lunar position, while in London in 1710–12. He issued various versions of the method, both in Latin and in Swedish, throughout his career. In 1766, at the age of 78, he presented his scheme for judgment by the Board of (...) class='Hi'>Longitude in London. The rich archive of Swedenborg's career allows an unusually detailed historical analysis of his longitude project, an analysis rather better documented than that available for the host of contemporary projectors who launched longitude schemes, submitted their proposals to the Board of Longitude, and have too often been ignored or dismissed by historians. This analysis uses the longitude work to illuminate key aspects of Swedenborg's wider enterprises, including his scheme to set up an astronomical observatory in southern Sweden to be devoted to lunar and stellar observation, his complex attitude to astronomical and magnetic cosmology, and his attempt to fit the notion of longitude into his visionary world-view. Swedenborg's programme also helps make better sense of the metropolitan and international networks of diplomatic and natural philosophical communication in which the longitude schemes were developed and judged. It emerges that his longitude method owed much to the established principles of earlier Baroque and Jesuit natural philosophy while his mature cosmology sought a rational and enlightened model of the universe. (shrink)