Klaas van Berkel, University of Groningen:

When the Dutch telescope was invented in 1608, the Low Countries were experiencing a civil war that was going on since the 1560's. The Dutch Republic that emerged from this struggle immediately became one of the major centers of the new science of nature. The intriguing question is: was there any connection between the ongoing war and the flowering of science in the new state? And was the war also responsible for the so-called decline of science in the southern provinces, which remained loyal to the Spanish crown? 

Discussion 

Coffee Break 

Rienk Vermij, University of Oklahoma

The circumstances surrounding the invention of the telescope will probably never be really clarified. Part of the problem lays in the way intellectual activity was organized in the period. Although the period around 1600 saw a lot of work that is by now considered as ground-breaking in the development of the sciences, more often than not such work remained marginal according to then prevalent standards of knowledge. Consequently, very little was put to paper. The telescope was one of the very first instances which gave people an inkling of the meaning and consequences some of the new practices could have. This paper will describe the intellectual landscape, in the Netherlands and Italy, in which the telescope was introduced, and how the new instrument helped to change it.

Floris Cohen, University of Utrecht: 

 In an across-the-board survey I shall discuss the emergence of two new types of mathematical instrument, the pendulum clock and the early telescope, and also four types of instrument that were made to serve fact-finding experimental science — musical instruments, the air pump, the microscope, and the later telescope. I shall compare the performance of these instruments in regard of the extent to which, and the various ways in which, they helped define, but also set limits to, revolutionary investigations undertaken in course of the 17th century.

Discussion 

Lunch 

Chair:  Huib Zuidervaart 

Mark Smith, University of Missouri, USA:

That Alhacen’s De aspectibus was enormously influential in the evolution of optics in the Latin West between roughly 1250 and 1600 is beyond dispute.  No less disputable is that Alhacen’s approach to optical analysis in that work is remarkably sophisticated.  Accordingly, Alhacen has generally been credited with having laid the theoretical and mathematical foundations for the development of modern optics, one of whose major steps lay in the invention and perfection of such optical devices as the telescope.  While this interpretation of Alhacen’s role in the development of modern optics is not implausible on its face, I will argue against it on the basis of a close look at Alhacen’s analysis of image-magnification in concave spherical mirrors and refracting media.  In the process, I will show that, as far as the development of modern catoptrics is concerned, Alhacen’s overall analysis of reflection and refraction represented more in the way of a dead end than of a positive contribution.  

Sven Dupré, Ghent University, Belgium & Utrecht University:

Around 1580 the English mathematician William Bourne wrote a letter to Lord Burghley in which he described for his potential but never-to-be patron a telescopic device. In the 1990s Colin Ronan, Joachim Rienitz and Ewan Whitaker interpreted the description in this letter as that of a telescope made out of a combination of a convex lens and a concave mirror, and they coined the term ‘Elizabethan telescope’ to refer to this device. While (as I will argue in this paper) I see no reason to follow their re-attribution of the invention of the telescope to an English mathematician almost thirty years prior to Hans Lipperhey’s patent application from Middelburg, the letter is, I think, of notable interest for the innovative optical concepts that Bourne used to describe the properties of the mirror and the lens of his telescopic device. In this paper I will show that Bourne’s telescopic device emerged out of a body of practical optical knowledge, which attempted to comprehend properties of the mirror, the lens and the camera obscura which had been conceptually alien to the perspectivist tradition of optics. The source of Bourne’s device in practical optical knowledge was also the reason that it immediately proved to be a dead end. The demands that it posed on the craft of lens and mirror-making of the period were too high to be easily met. However, in a broader perspective Bourne’s device was also the product of a newly emerging culture of optics. This paper will discuss how early modern and post-Keplerian optics emerged out of the competition between this and other cultures of optics and the appropriation of the conceptual innovations and confusions in the perspectivist tradition in the wake of the invention of the telescope.

Tea break

Katrien Vanagt, History of Science and Technology department, Twente University:

At the eve of the invention of the telescope, eyeglasses were widely spread and commonly used.  Yet a close study of medical texts shows that, despite their spectacular results, spectacles were rarely advocated as a solution for diminished vision.  The physician’s attitude towards the use of eyeglasses was somehow ambiguous.  Besides culturally shaped factors, a great deal of this ambiguity seems due to the difficulty of fitting eyeglasses within the holistic remedies in use, as well as to doubts about how they influenced vision.  For speaking about looking glasses is not only about vision, but also about defective vision.  And this is where the problem arises.  Whereas opticians could speak about how vision took place in ideal circumstances, physicians had to formulate a theory of vision that was in accordance with their views on the diseased eye. The attitude changed during the seventeenth century, a change which can clearly be linked to the evolution in ocular anatomy, strongly influenced by optical insights, whereby the eye is no longer considered in relation to the body, but to the world outside.

Daniëlle Caluwé, Brussels, Belgium: 

In this contribution the material evidence of mirrors, spectacles and looking glasses will be assessed on the basis of the archaeological finds in the Duchy of Brabant from the fifteenth- till the eighteenth- century. Furthermore an investigation of sixteenth-century Antwerp inventories shows the early use of such objects. These results are confronted with seventeenth-century Leiden inventories in order to evaluate frequency, distribution and specific characteristics. The results have to be situated in the historical context of regional and local production. Therefore the historical evidence on production, trade and distribution has to be taken into account, in order to evaluate the technical knowledge and its transfer from the earliest period onwards.

Discussion 

End of Afternoon session 

[Dinner at own expense] 

Evening Programme

Commemoration for the general public

Albert van Helden

Roosevelt Academy Choir

Coffee break

Drinks