In diesem Aufsatz wird ein bisher unbekannter Traktat zur Dioptrik von Johannes Hudde veröffentlicht. Wie aus der Korrespondenz von Christiaan Huygens mit seinem Lehrer Frans van Schooten hervorgeht, ist dieser Traktat bereits im Jahre 1656 gedruckt worden . Leider sind von dieser Auflage heute keine Exemplare mehr bekannt. Der Text wird hier dargestellt an Hand zweier handschriftlicher Kopien, eine im Besitz der Royal Society in London, die andere im Leibniz-Nachlaß in Hannover. Auf der Londoner Kopie wird Hudde als Verfasser angegebe, (...) und durch einen Brief Spinozas an Hudde, worin auf den Traktat und eine darin enthaltene Abbildung hingewiesen wird, läßt sich bestätigen, daß er der Autor ist. - Das Problem, womit Hudde sich in diesem Traktat beschäftigt, gilt der sphärischen Aberration: Wie stellt man Linsen oder optische Instrumente ohne Aberration her? Für Linsen mit gewissen ovalen Formen hatte Descartes bereits eine Lösung vorgeschlagen. Hudde aber weist darauf hin, daß diese Lösung nur theoretische Bedeutung hat; in der Praxis ist es zu schwierig, solche Linsen herzustellen. Für eine praktische Lösung entwickelt Hudde eine andere Methode. Er zeigt, daß die sphärische Aberration von einfachen kugelförmigen Linsen in manchen Fällen zu vernachlässigen ist. Der Brennpunkt ist dann zwar kein mathematischer, aber, wie er es nennt, doch ein mechanischer Punkt. Diese Behauptung wird mathematisch ausgearbeitet. Ein solches Vorgehen war in der Dioptrik damals ungewöhnlich. Obwohl der Traktat aus rein mathematischer Sicht wenig Aufsehenerregendes enthält, verdient er wegen seines methodischen Vorgehens doch Beachtung. Huddes mathematisch genaue Behandlung von Ungenauigkeiten war zu seiner Zeit sehr originell. (shrink)

A letter written by Christiaan Huygens to David Gregory is published here for the first time. After an introduction about the contacts between the two correspondents, an annotated English translation of the letter is given. The letter forms part of the wider correspondence about the ‘new calculus’, in which L'Hospital and Leibniz also participated, and gives some new evidence about Huygens's ambivalent attitude towards the new developments. Therefore, two mathematical passages in the letter are discussed separately. An appendix contains the (...) original Latin text. (shrink)

The international debate on the animal machine was initiated by the preface that the Dutch philosopher and later professor of medicine Florentius Schuyl in 1662 added to his Latin translation of Descartes’ Treatise on Man. Schuyl defended the animal machine in reaction to the vehement attacks, mostly in the vernacular, against the philosophy of Descartes in the Dutch Republic in the 1650s, wherein the theory of the animal machine had become one of the flashpoints. These polemics were part of a (...) power struggle, not a quest for philosophical truth. Schuyl focused on the points that had appeared as controversial in these debates: biblical exegesis, arguments from common sense, and to some extent physiology, but ignored wider philosophical questions. Questions about the soul and human uniqueness came to the fore only when his work was picked up in a new context, the international republic of letters. Schuyl's preface is therefore an interesting example of knowledge taking shape by circulation. (shrink)

ABSTRACT At first sight, the English astronomer John Bainbridge's treatise on the great comet of 1618 appears rather idiosyncratic. It regards the comet as a favourable omen and applies an astrological explanation that is completely metaphorical. At closer look, however, Bainbridge's interpretation appears well in line with the meaning commonly attributed to comets at the time. We should realize that an important function of the discourse on prodigious phenomena, such as comets, was to uphold and strengthen the confessional social order. (...) Moreover, the treatise was addressed to the King rather than to the common population. To understand the early modern interpretation of comets, the processes of confessionalization and de-confessionalization deserve more consideration. (shrink)

Geschiedenis van het verschuivende mens- en wereldbeeld tijdens de achttiende eeuw waardoor de nadruk kwam te liggen op de ratio.

Aristotle described the earth as a cold and dry body and paid no attention to the phenomenon of terrestrial heat. Renaissance physicians, by contrast, when seeking to understand the origin of hot springs in the context of their balneological studies, came to defend a theory of subterranean fires. This tradition, which started in Italy, became widely known through the works of Georgius Agricola. But although it had implications for the explanation of further natural phenomena, it remained almost exclusively confined to (...) medical circles. As far as physics as an academic discipline was concerned, the ideas concerning subterranean fire were hardly taken note of. Only with the collapse of Aristotelian philosophy in the seventeenth century could these by then "old innovations" obtain a wider significance. (shrink)

In the first half of the 17th century, Dutch astronomers rapidly abandoned the practice of astrology. By the second half of the century, no trace of it was left in Dutch academic discourse. This abandonment, in its early stages, does not appear as the result of criticism or skepticism, although such skepticism was certainly known in the Dutch Republic and leading humanist scholars referred to Pico’s arguments against astrological predictions. The astronomers, however, did not really refute astrology, but simply stopped (...) paying attention to it, as other questions became the focus of their scholarship. The underlying physical view of the world, with its idea of celestial influences, remained in vigor much longer. Even convinced anti-Aristotelians, in explaining the world, tried to account for the effects of the oppositions and conjunctions of planets, and similar elements. It is only with Descartes that the by now widespread skepticism about predictions found expression in a philosophy that denied celestial influence. (shrink)