Rounding numbers: Ptolemy’s calculation of the Earth–Sun distance

In this article, I analyze the coincidence of the prediction of the Earth–Sun distance carried out by Ptolemy in his Almagest and the one he carried out, with another method, in the Planetary Hypotheses. In both cases, the values obtained for the Earth–Sun distance are very similar, so that the great majority of historians have suspected that Ptolemy altered or at least selected the data in order to obtain this agreement. In this article, I will provide a reconstruction of some way in which Ptolemy could have altered or selected the data and subsequently will try to argue in favor of its historical plausibility.     

An unusual silver celestial planisphere in the Whipple Museum

An unusual silver celestial planisphere is held in the collection of the Whipple Museum of the History of Science (Wh.1762); little information about this object is recorded in the museum’s documentation. A comparison of this silver example with celestial planispheres printed on paper, coupled with the consideration of other aspects of the lives and work of the cartographers and instrument-makers involved in producing such objects, suggests some possibilities regarding its production. Through this individual case study, I aim to demonstrate that the careful examination of an individual instrument, coupled with an understanding of the class of instruments to which it belongs and the milieu in which it was produced, can result in a deeper understanding of any given artefact, its circumstances of design and manufacture, and its intended use and users.     

Thomas Harriot—Sir Walter Ralegh's tutor—On population

The empiricism of eighteenth-century experimental science meant that the development of scientific instruments influenced the formulation of new concepts; a two-way process for new theory also affected instrument design. This relationship between concept and instrumentation will be examined by tracing the development of electrical instruments and theory during this period. The different functions fulfilled by these devices will also be discussed. Empiricism was especially important in such a new field of research as electricity, for it gave rise to phenomena that could not have been predicted by theory alone. However, the interpretation of these phenomena, and what the natural philosopher thought he observed, were often unconsciously determined by current ideas and attitudes; the interaction between instrumentally induced phenomena and observation was more complex than was realized at the time. The shortcomings of this empirical approach will be discussed. In the case of electricity this became increasingly apparent during the latter part of the century. The many discoveries had to be placed in a unifying framework before new advances could be made. Instruments, however, continued to play an important role in scientific progress, for they made visible what was hidden in nature.     

I am knowledge. Get me out of here! On localism and the universality of science

It has become increasingly common in historiography of science to understand science and its products as inherently local. However, this orientation is faced with three problems. First, how can one explain the seeming universality of contemporary science? Second, if science is so reflective of its local conditions of production, how can it travel so effortlessly to other localities and even globally? And third, how can scientific knowledge attain validity outside its context of origin? I will argue that the notion of standardization and theories of delocalization manage to explain the ‘globality’ of science, but that localism denies ‘universality’ if it is understood non-spatially. Further, localism limits the validity of scientific knowledge unacceptably inside the laboratory walls or other boundaries of knowledge creation. This is not consistent with scientific practice. I will consider on what grounds extra-local knowledge inferences that transcend the boundaries of locality could be seen as justified.     

Mass production ofSpirulina

Conclusions A large industrial production ofSpirulina and its products is possible already now, thanks to technological development. This production capacity and its excellent properties as a food have justified the effort to overcome the barriers of sanitary regulations in countries such as Mexico, Japan, Canada, the United States of America, France, Great Britain, the Federal Republic of Germany, New Zealand, Australia, Korea etc., where its consumption is expanding. In the forecoming years, the production ofSpirulina is expected to reach several thousands of tons yearly, which will initiate a massive production and consumption program.Spirulina, which Farrar⁹ calls glimpse of the Aztec food technology, will undergo a broad distribution and its alimentary benefits will be within everyone's reach.At present, Sosa Texcoco is ready to market 500 tons more in 1982, and is working on another expansion of 2000 tons per year which should be realized by 1983.     

Newton’s notion and practice of unification

In this paper I deal with a neglected topic with respect to unification in Newton’s Principia. I will clarify Newton’s notion (as can be found in Newton’s utterances on unification) and practice of unification (its actual occurrence in his scientific work). In order to do so, I will use the recent theories on unification as tools of analysis (Kitcher, Salmon and Schurz). I will argue, after showing that neither Kitcher’s nor Schurz’s account aptly capture Newton’s notion and practice of unification, that Salmon’s later work is a good starting point for analysing this notion and its practice in the Principia. Finally, I will supplement Salmon’s account in order to answer the question at stake.     

Making sense of Day 1 of the Two New Sciences: Galileo’s Aristotelian-inspired agenda and his Jesuit readers

This study proposes an explanation for the choice of topics Galileo addressed in Day 1 of his 1638 Two New Sciences, a section of the work which has long puzzled historians of science. I argue that Galileo’s agenda in Day 1, that is the topics he discusses and the questions he poses, was shaped by contemporary teaching commentaries on Books 3 through 8 of Aristotle’s Physics. Building on the insights and approach of theorists of reader reception, I confirm this interpretation by examining the response of professors of natural philosophy at the Jesuit Collegio Romano to Galileo’s text.     

Legionella pneumophila down-regulates MHC class I expression of human monocytic host cells and thereby inhibits T cell activation

Legionella (L.) pneumophila, the causative agent of Legionnaires disease, is an intracellular pathogen of alveolar macrophages that resides in a compartment displaying features of endoplasmatic reticulum (ER). In this study, we show that intracellular multiplication of L. pneumophila results in a remarkable decrease in MHC class I expression by the infected monocytes. During intracellular multiplication, L. pneumophila absorbs ER-resident chaperons such as calnexin and BiP, molecules that are required for the correct formation of the MHC class I complex. Due to reduced MHC class I expression, stimulation of allogeneic blood mononuclear cells was severely inhibited by infected host cells but cytotoxicity of autologous natural killer cells against Legionella-infected monocytes was not enhanced. Thus, reduced expression of MHC class I in infected monocytes may resemble a new immune escape mechanism induced by L. pneumophila.Received 22 November 2004; received after revision 27 December 2004; accepted 5 January 2005     

John Dalton’s puzzles: from meteorology to chemistry

Historical research on John Dalton has been dominated by an attempt to reconstruct the origins of his so-called “chemical atomic theory”. I show that Dalton’s theory is difficult to define in any concise manner, and that there has been no consensus as to its unique content among his contemporaries, later chemists, and modern historians. I propose an approach which, instead of attempting to work backward from Dalton’s theory, works forward, by identifying the research questions that Dalton posed to himself and attempting to understand how his hypotheses served as answers to these questions. I describe Dalton’s scientific work as an evolving set of puzzles about natural phenomena. I show how an early interest in meteorology led Dalton to see the constitution of the atmosphere as a puzzle. In working on this great puzzle, he gradually turned his interest to specifically chemical questions. In the end, the web of puzzles that he worked on required him to create his own novel philosophy of chemistry for which he is known today.     

The elusive engine in <Emphasis Type="Italic">Myxococcus xanthus</Emphasis> gliding motility

Bacterial motility is essential for chemotaxis, virulence and complex social interactions leading to biofilm and fruiting body formation. Although bacterial swimming in liquids with a flagellum is well understood, little is known regarding bacterial movements across solid surfaces. Gliding motility, one such mode of locomotion, has remained largely mysterious because cells move smoothly along their long axis in the absence of any visible organelle. In this review, I discuss recent evidence that focal adhesion systems mediate gliding motility in the social bacterium Myxococcus xanthus and combine this evidence with previous work to suggest a new working hypothesis inspired from knowledge in apicomplexan parasites. I then propose experimental directions to test the model and compare it to other pre-existing models. Finally, evidence on gliding mechanisms of selected organisms are presented to ask whether some features of the model have precedents in other bacteria and whether this complex biological process could be explained by a single mechanism or involves multiple distinct mechanisms. Received 12 April 2007; received after revision 8 June 2007; accepted 27 June 2007     

Francesco Patrizi’s two books on space: geometry, mathematics, and dialectic beyond Aristotelian science

Francesco Patrizi was a competent Greek scholar, a mathematician, and a Neoplatonic thinker, well known for his sharp critique of Aristotle and the Aristotelian tradition. In this article I shall present, in the first part, the importance of the concept of a three-dimensional space which is regarded as a body, as opposed to the Aristotelian two-dimensional space or interval, in Patrizi’s discussion of physical space. This point, I shall argue, is an essential part of Patrizi’s overall critique of Aristotelian science, in which Epicurean, Stoic, and mainly Neoplatonic elements were brought together, in what seems like an original theory of space and a radical revision of Aristotelian physics. Moreover, I shall try to show Patrizi’s dialectical method of definition, his geometrical argumentation, and trace some of the ideas and terms used by him back to Proclus’ Commentary on Euclid. This text of Proclus, as will be shown in the second part of the article, was also important for Patrizi’s discussion of mathematical space, where Patrizi deals with the status of mathematics and redefines some mathematical concepts such as the point and the line according to his new theory of space.     

Male tarsal sex-comb teeth pattern in theDrosophila bipectinata complex

Summary Species within theD. bipectinata species complex pose problems experimentally because of their morphological similarity. By measuring the number of teeth in each row of the male tarsal sex-comb, an unknown specimen can be allocated to a hybrid or parental group by means of a discriminant function. This paper describes which rows of the sex-comb are the best discriminators for particular comparisons.Acknowledgments. We thank L. Anderson and P. Rowbury for technical and research assistance, Dr I. Bock for providing fly stocks and for his continued interest and helpful discussions, and the Australian Research Grants Scheme for financial assistance.     

Explanation,understanding, and unrealistic models

How can false models be explanatory? And how can they help us to understand the way the world works? Sometimes scientists have little hope of building models that approximate the world they observe. Even in such cases, I argue, the models they build can have explanatory import. The basic idea is that scientists provide causal explanations of why the regularity entailed by an abstract and idealized model fails to obtain. They do so by relaxing some of its unrealistic assumptions. This method of ‘explanation by relaxation’ captures the explanatory import of some important models in economics. I contrast this method with the accounts that Daniel Hausman and Nancy Cartwright have provided of explanation in economics. Their accounts are unsatisfactory because they require that the economic model regularities obtain, which is rarely the case. I go on to argue that counterfactual regularities play a central role in achieving ‘understanding by relaxation.’ This has a surprising implication for the relation between explanation and understanding: Achieving scientific understanding does not require the ability to explain observed regularities.     

The functional bias of the dual nature of technical artefacts program

In 2006, in a special issue of this journal, several authors explored what they called the dual nature of artefacts. The core idea is simple, but attractive: to make sense of an artefact, one needs to consider both its physical nature—its being a material object—and its intentional nature—its being an entity designed to further human ends and needs. The authors construe the intentional component quite narrowly, though: it just refers to the artefact’s function, its being a means to realize a certain practical end. Although such strong focus on functions is quite natural (and quite common in the analytic literature on artefacts), I argue in this paper that an artefact’s intentional nature is not exhausted by functional considerations. Many non-functional properties of artefacts—such as their marketability and ease of manufacture—testify to the intentions of their users/designers; and I show that if these sorts of considerations are included, one gets much more satisfactory explanations of artefacts, their design, and normativity.     

Writing tea’s empire

The Almagest of Ptolemy (mid-second century ad) contains eleven dated reports of observations of the positions of planets made during the third century bc in Babylon and Hellenistic Egypt. The present paper investigates the character, purpose, and conventions of the observational programmes from which these reports derive, the channels of their transmission to Ptolemy's time, and the fidelity of Ptolemy's presentation of them. Like the Babylonian observational programme, about which we have considerable knowledge through cuneiform documents, the Greco-Egyptian ones were not directed towards the deduction of mathematical models of celestial motion but appear to have investigated patterns, correlations, and periodicities of phenomena. Ptolemy's immediate sources most likely were not the original series of observational records, but treatises by various astronomers of the intervening four centuries, including Hipparchus. While Ptolemy does not appear to have tampered with the wording of the reports, he faced difficulties and uncertainties in interpreting them; critically, he lacked sufficiently detailed information about the ancient calendars to be able to convert the reported dates accurately into his own chronological framework based on the Egyptian calendar.