This study, presenting a history of the measurement of light intensity from its first hesitant emergence to its gradual definition as a scientific subject, explores two major themes. The first concerns the adoption by the evolving physics and engineering communities of quantitative measures of light intensity around the turn of the twentieth century. The mathematisation of light measurement was a contentious process that hinged on finding an acceptable relationship between the mutable response of the human eye and the more easily (...) stabilised, but less encompassing, techniques of physical measurement. -/- A second theme is the exploration of light measurement as an example of ‘peripheral science’. Among the characteristics of such a science, I identify the lack of a coherent research tradition and the persistent partitioning of the subject between disparate groups of practitioners. Light measurement straddled the conventional categories of ‘science’ and ‘technology’, and was influenced by such distinct factors as utilitarian requirements, technological innovation, human perception and bureaucratisation. Peripheral fields such as this, which may be typical of much of modern science and technology, have hitherto received little attention from historians. -/- These themes are pursued with reference to the social and technological factors which were combined inextricably in the development of the subject. The intensity of light gained only sporadic attention until the late nineteenth century. Measured for the utilitarian needs of the gas lighting industry from the second half of the century, light intensity was appropriated by members of the nascent electric lighting industry, too, in their search for a standard of illumination. By the turn of the century the ‘illuminating engineering movement’ was becoming an organised, if eclectic, community which promoted research into and standards for the measurement of light intensity. -/- The twentieth-century development of the subject was moulded by organisation and institutionalisation. Between 1900 and 1920, the new national and industrial laboratories in Britain, America and Germany were crucial in stabilising the subject. In the inter-war period, committees and international commissions sought to standardise light measurement and to promote research. Such government- and industry-supported delegations, rather than academic institutions, were primarily responsible for the ‘construction’ of the subject. Practitioners increasingly came to interpret the three topics of photometry (visible light measurement), colorimetry (the measurement of colour) and radiometry (the measurement of invisible radiations) as aspects of a broader study, and enthusiastically applied them to industrial and scientific problems. -/- From the 1920s, the long-established visual methods of observation were increasingly replaced by physical means of light measurement, a process initially contingent on scientific fashion more than demonstrated superiority. New photoelectric techniques for measuring light intensity engendered new commercial instruments, a trend which accelerated in the following decade when photometric measurement was applied with limited success to a range of industrial problems. Seeds sowed in the 1920s – namely commercialisation and industrial application, the transition from visual to ‘physical’ methods, and the search for fundamental limitations in light measurement – gave the subject substantially the form it was to retain over the next half-century. (shrink)

We introduce stellar photometry, its purpose and relationship to other astronomical quantities, presenting it within the context of astronomical research at the Vatican Observatory. We demonstrate the usefulness of the Vilnius Photometric System previously shown at Vilnius Astronomical Obs., Edinburgh Royal Obs., and Università di Roma “La Sapienza”, and then adopted by the Vatican Observatory for use with its Vatican Advanced Technology Telescope on Mount Graham, AZ, USA. The development of astronomical observations has led from photographic plates, through photoelectric (...) detectors to the use of sensitive CCD cameras. Expanding the photoelectric databank of “Vilnius Stars”, we describe the development of new techniques of data-acquisition, calibration to photometric standards, stellar classification and interstellar-matter characterization. Looking ahead, we briefly describe the extensive data set, and our plans for further detailed analyses. (shrink)

Contrary to what has been asserted or implied by Mach and more recent writers, the law of illumination and the study of photometry were not ignored in the years between Kepler's first enunciation of the former in 1609 and Bouguer's Essai on the latter in 1729. The law of illumination was in fact denied in 1613 by Aguilonius. It was probably rediscovered independently and certainly reformulated in more modern terms by Mersenne and Castelli in 1634, and by Boulliau in (...) 1638. It was again formulated and this time demonstrated empirically by Montanari no later than 1676, and possibly as early as 1634 by Castelli. Although neither the law nor photometry were major concerns before Bouguer, they were not completely neglected either. (shrink)

"Der geschichtliche Sinn, welcher schon das Altertum auszeichnete, bewahrte sich auch auf unserm Gebiete, und es hat schon in fruher Zeit nicht an Versuchen gefehlt, den Entwicklungsgang des Wissens bis zu einem gewissen Termine zu schildern. Nach Diogenes von Laerte, einem freilich nicht immer vollig zuverlassigen Gewahrsmann, hat schon ein Schuler des Aristoteles, der als Naturforscher bekanntere Theophrast, Geschichtswerke uber Arithmetik, Geometrie und Astronomie verfasst, von denen sich jedoch hochstens insofern eine Spur erhalten hat, als nach den ausgezeichneten Untersuchungen von (...) Diels bei einer ganzen Reihe spatlateinischer und spatgriechischer Autoren Anklange an historische Angaben Theophrasts zu finden sind. Ahnliches gilt von der angeblich geometrischen Schrift des Xenokrates, deren ebenfalls Diogenes Erwahnung tut." [...] Der bedeutende Philosoph und Philosophiehistoriker Dr. Wilhelm Windelband (1848-1915) gilt als Begrunder der sudwestdeutschen Schule (auch Badische Schule ), die eine Richtung des Neukantianismus darstellt. Windelbands Hauptaugenmerk galt der Abgrenzung von Natur- und Kulturwissenschaften. Sein wichtigster Schuler war Heinrich Rickert. Sigmund Gunther lebte von 1848 - 1923 und gilt als einer der wichtigsten Mathematikhistoriker. Er wurde mit der Dissertation "Studien zu theoretischen Photometrie" promoviert. In dem vorliegenden Werk gehen beide Autoren ausfuhrlich auf die geschichtlichen Hintergrunde der Naturwissenschaften und der Philosophie ein. Das Buch erschien ursprunglich als funfter Band im "Handbuch der klassischen Altertums-Wissenschaft" und wurde 1888 erstmals veroffentlicht. Der Verlag der Wissenschaften verlegt historische Literatur bekannter und unbekannter wissenschaftlicher Autoren. Dem interessierten Leser werden so teilweise langst nicht mehr verlegte Werke wieder zugangig gemacht. Das vorliegende Buch ist ein unveranderter Nachdruck der Originalausgabe.". (shrink)

Deep brain stimulation is a clinical intervention for the treatment of movement disorders. It has also been applied to the treatment of psychiatric disorders such as depression, anorexia nervosa, obsessive-compulsive disorder, and schizophrenia. Psychiatric disorders including schizophrenia, bipolar disorder, and major depression can lead to psychosis, which can cause patients to lose touch with reality. The ventral tegmental area, located near the midline of the midbrain, is an important region involved in psychosis. However, the clinical application of electrical stimulation of (...) the VTA to treat psychotic diseases has been limited, and related mechanisms have not been thoroughly studied. In the present study, hyperlocomotion and stereotyped behaviors of the mice were employed to mimic and evaluate the positive-psychotic-like behaviors. We attempted to treat positive psychotic-like behaviors by electrically stimulating the VTA in mice and exploring the neural mechanisms behind behavioral effects. Local field potential recording and in vivo fiber photometry to observe the behavioral effects and changes in neural activities caused by DBS in the VTA of mice. Optogenetic techniques were used to verify the neural mechanisms underlying the behavioral effects induced by DBS. Our results showed that electrical stimulation of the VTA activates local gamma-aminobutyric acid neurons, and dopamine neurons, reduces hyperlocomotion, and relieves stereotyped behaviors induced by MK-801 injection. The results of optogenetic manipulation showed that the activation of the VTA GABA neurons, but not DA neurons, is involved in the alleviation of hyperlocomotion and stereotyped behaviors. We visualized changes in the activity of specific types in specific brain areas induced by DBS, and explored the neural mechanism of DBS in alleviating positive psychotic-like behaviors. This preclinical study not only proposes new technical means of exploring the mechanism of DBS, but also provides experimental justification for the clinical treatment of psychotic diseases by electrical stimulation of the VTA. (shrink)

En dépit de la difficulté présentée par les mesures d'éclat, John Michell construisit au dix-huitième siècle une échelle de magnitude étonnante de précision et de rigueur. Mais il n'indique pas ses propres méthodes. Sans doute transposa-t-il aux étoiles les méthodes de Bouguer dont l'ouvrage faisait alors autorité en matière de photométrie. Son travail, dont il se contente d'exposer très brièvement les résultats sans en développer les principes, restera ignoré des autres astronomes.

2003 Paul Bunge Prize of the Hans R. Jenemann Foundation for the History of Scientific Instruments Judging the brightness and color of light has long been contentious. Alternately described as impossible and routine, it was beset by problems both technical and social. How trustworthy could such measurements be? Was the best standard of intensity a gas lamp, an incandescent bulb, or a glowing pool of molten metal? And how much did the answers depend on the background of the specialist? A (...) History of Light and Colour Measurement: Science in the Shadows is a history of the hidden workings of physical science-a technical endeavor embedded in a social context. It argues that this "undisciplined" subject, straddling academia, commerce, and regulation, may be typical not only of 20th century science, but of its future. Attracting scientists, engineers, industrialists, and artists, the developing subject produced a new breed of practitioners having mixed provenance. The new measurers of light had to decide the shape not only of their specialism but of their careers: were they to be a part of physics, engineering, or psychology? The physical scientists who dominated the subject into the early 20th century made their central aim the replacement of the problematic human eye with physical detectors of light. For psychologists between the wars, though, describing the complexity of color was more important than quantifying a handful of its dimensions. And after WWII, military designers shaped the subject of radiometry and subsumed photometry and colorimetry within it. Never attaining a professional cachet, these various specialists moved fluidly between science and technology; through government, industry, and administration. (shrink)

Given a subject so imbued with contention and conflicting theoretical stances, it is remarkable that automated instruments ever came to replace the human eye as sensitive arbiters of color specification. Yet, dramatic shifts in assumptions and practice did occur in the first half of the twentieth century. How and why was confidence transferred from careful observers to mechanized devices when the property being measured – color – had become so closely identified with human physiology and psychology? A fertile perspective on (...) the problem is via the history of science and technology, paying particular attention to social groups and disciplinary identity to determine how those factors affected their communities’ cognitive territory. There were both common and discordant threads motivating the various technical groups that took on the problems of measuring light and color from the late nineteenth century onwards, and leading them towards the development of appropriate instruments for themselves. The transition from visual to photoelectric methods could be portrayed as a natural evolution, replacing the eye by an alternative roviding more sensitivity and convenience – indeed, this is the conventional positivist view propounded by technical histories. However, the adoption of new measurement technologies seldom is simple, and frequently has a significant cultural component. Beneath this slide towards automation lay a raft of implicit assumptions about objectivity, the nature of the observer, the role of instruments, and the trade-offs between standardization and descriptive power. While espousing rational arguments for a physical detector of color, its proponents weighted their views with tacit considerations. The reassignment of trust from the eye to automated instruments was influenced as much by the historical context as by intellectual factors. I will argue that several distinct aspects were involved, which include the reductive view of color provided by the trichromatic theory; the impetus provided by its association with photometry; the expanding mood for a quantitative and objective approach to scientific observation; and, the pressures for commercial standardization. As suggested by these factors, there was another shift of authority at play: from one technical specialism to another. The regularization of color involved appropriation of the subject by a particular set of social interests: communities of physicists and engineers espousing a ‘physicalist’ interpretation, rather than psychologists and physiologists for whom color was conceived as a more complex phenomenon. Moreover, the sources for automated color measurement, and instrumentation for measuring color, were primarily from the industrial sphere rather than from academic science. To understand these shifts, then, this chapter explores differing views of the importance of observers, machines and automation. (shrink)

© 2017. The American Astronomical Society. All rights reserved.We present new observations of the low-mass companion to HD 984 taken with the Gemini Planet Imager as a part of the GPI Exoplanet Survey campaign. Images of HD 984 B were obtained in the J and H bands. Combined with archival epochs from 2012 and 2014, we fit the first orbit to the companion to find an 18 au orbit with a 68% confidence interval between 14 and 28 au, an eccentricity (...) of 0.18 with a 68% confidence interval between 0.05 and 0.47, and an inclination of 119°with a 68% confidence interval between 114°and 125°. To address the considerable spectral covariance in both spectra, we present a method of splitting the spectra into low and high frequencies to analyze the spectral structure at different spatial frequencies with the proper spectral noise correlation. Using the split spectra, we compare them to known spectral types using field brown dwarf and low-mass star spectra and find a best-fit match of a field gravity M6.5 ±1.5 spectral type with a corresponding temperature of K. Photometry of the companion yields a luminosity of log=2.88 ± 0.07 dex with DUSTY models. Mass estimates, again from DUSTY models, find an age-dependent mass of 34 ±1 to 95 ±4 M Jup. These results are consistent with previous measurements of the object. (shrink)

The measurement of light and colour has always been a peripheral science. Light became a 'disciplined' quantity over the period of a century, but the specialist communities that measured it did not. The quantification of visible light (photometry), colour (colorimetry), and radiant intensity (radiometry) involved distinct communities of physicists, psychologists, technicians and engineers. -/- This chapter of _Science in the Shadows_ examines how the measurement of non-visible light became the domain of post Second World War military engineers and classified (...) development programmes. (shrink)