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)

(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.

(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)

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)

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)

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)

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)

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)

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)

Successful prototype marine chronometers, developed by Harrison and others in the eighteenth century, stimulated a sector of the British watchmaking industry to supply Admiralty and commercial demand for this instrument. Chronometers, like other British-made timepieces, were constructed by an elaborate pre-industrial method of production. The instrument's static technology and extreme durability meant replacement demand was minimal, and new demand was low relative to existing stock and the industry's capacity. The First World War created a final surge of demand that left (...) supplies far in excess of peacetime needs; and a new technology—radio transmissions of time signals—offered an alternative method of determining Greenwich time, and thus longitude, at sea. (shrink)

The magnet served three interests of Restoration mechanical philosophers: it provided a model of cosmic forces, it suggested a solution to the problem of longitude determination, and evidence of its corpuscular mechanism would silence critics. An implicit condition of William Gilbert's ‘magnetic philosophy’ was the existence of a unique, immaterial magnetic virtue. Restoration mechanical philosophers, while claiming descent from their compatriot, worked successfully to disprove this, following an experimental regime of Henry Power. Magnetic philosophy lost its coherence and became (...) subsumed in the study of effluvia. This contradiction of a distinct, yet mechanical magnetic philosophy came to a head in 1684 in an argument between Robert Hooke and Martin Lister. An effluvial explanation of magnetism introduced great complexity to the North-seeking behaviour of compass needles, and undermined the already troubled longitude programme. Thus magnetic philosophy no longer furthered the interests which had maintained it, and it was abandoned. (shrink)

In this study I attempt to provide an answer to the question how the Babylonian scholars arrived at their mathematical theory of planetary motion. Although no texts are preserved in which the Babylonians tell us how they did it, from the surviving Astronomical Diaries we have a fairly complete picture of the nature of the observational material on which the scholars must have based their theory and from which they must have derived the values of the defining parameters. Limiting the (...) discussion to system A theory of the outer planets Saturn, Jupiter and Mars, I will argue that the development of Babylonian planetary theory was a gradual process of more than a century, starting sometime in the fifth century BC and finally resulting in the appearance of the first full-fledged astronomical ephemeris around 300 BC. The process of theory formation involved the derivation of long “exact” periods by linear combination of “Goal–Year” periods, the invention of a 360° zodiac, the discovery of the variable motion of the planets and the development of the numerical method to model this as a step function. Longitudes of the planets in the Babylonian zodiac could be determined by the scholars with an accuracy of 1° to 2° from observations of angular distances to Normal Stars with known positions. However, since the sky is too bright at first and last appearances of the planets and at acronychal rising for nearby stars to be visible, accurate longitudes as input for theoretical work could only be determined when the planets were near the stationary points in their orbits. In this study I show that the Babylonian scholars indeed based their system A modeling of the outer planets on planetary longitudes near stations, that their system A models of Saturn and Jupiter provided satisfactory results for all synodic phenomena, that they realized that their system A model of Mars did not produce satisfactory results for the second station so that separate numerical schemes were constructed to predict the positions of Mars at second station from the model at first station, and finally that their system A model for Mars provided quite poor predictions of the longitude of Mars at first and last appearances over large stretches of the zodiac. I further discuss ways in which the parameters of the system A models may have been derived from observations of the outer planets. By analyzing contemporaneous ephemerides from Uruk of four synodic phenomena of Jupiter from the second century BC, I finally illustrate how the Babylonian scholars may have used observations of Normal Star passages of planets to choose the initial conditions for their ephemerides. (shrink)

The film Nosferatu (1922) has graffiti created by the character of the madman Knock on the walls of his cell. This motif, which I call the ‘madman’s wall’, has accompanied depictions of lunatics since the beginning of the eighteenth century. This article examines the origin, transformations and functions of this motif. The popularisation of the motif originates with the longitude diagram in the last plate of A Rake’s Progress (1735) by William Hogarth, which subsequently found its way into the (...) works of Hogarth’s plagiarists and influenced illustrations of asylum interiors in the first half of the nineteenth century. The madman’s wall also appears in literature, such as the popular novel The Father and Daughter (1801) by Amelia Opie, which was plagiarised and dramatised, and the legend of the poet Charles Smart, who allegedly wrote his poem on the walls of his cell. The main prerequisite for the madman’s wall is the dungeon-like image of the asylum—presenting it as a prison. It is usually the author of the graffiti who displays the signs of madness, not the wall itself. As society distanced itself from the image of the asylum as a dungeon, the madman’s wall disappeared after the 1850s. Paradoxically, many reports about the authentic wall art of asylum patients emerged in the press after the 1850s. The madman’s wall in Nosferatu is the first example after an approximately seventy-year absence and could be a product of the period interest of avant-garde artists in the art of the mentally ill. (shrink)

I wouldn't recommend this to the faint of heart. It's a bit terrifying. It's well written, but it tells the long and tangled tale of how theories of the ENSO phenomenon evolved from 1969 to 1998 — a period that saw much progress, but did not end with a neat, clean understanding of this phenomenon. It's packed with hundreds of references, and sprinkled with somewhat intimidating remarks like: The Fourier decomposed longitude and time dependence of these eigensolutions obey dispersion (...) relations familiar to every physical oceanographer... Nonetheless I found it fascinating — so, I'll pick off one small idea and explain it now. (shrink)