‘Zo'n mooie machine, waarvan de kwaliteit door alle astronomen wordt erkend.’ Een biografie van een vrijwel niet gebruikte telescoop

Abstract

This article presents the biography of a remarkable instrument: the so-called Van de Wall-telescope, now in the collection of Museum Boerhaave at Leyden. At the time of its construction (c. 1742) this instrument represented not only the state of the art, but for decades it was also the largest telescope in the Netherlands. Its designer and owner was the Amsterdam merchant Jacobus van de Wall (1700-1782). This 'gentleman-scientist' devoted himself to scientific endeavours, but these were shaped by social desirability rather than scientific curiosity. Scientific instruments were at that time very fashionable. This study reveals that Van de Wall was primarily interested in the craft of making optical instruments. The instrument was only scarcely used for astronomical purposes. So in spite of the fact that the telescope was praised for its quality by several contemporary astronomers who visited Van de Wall's private observatory at Amsterdam, it played no role whatsoever in the research of the heavens. This did not change after the instrument had been donated, in 1782, to Leyden University. The Leyden Observatory was not equipped for the telescope. In the beginning of the nineteenth century the telescope became obsolete, because the mirror had become dull. Since then the telescope was only used as an icon for astronomy, ending its career as a hat-and-coat-stand in the hall of the in 1861 newly erected Leyden Observatory.