The Natural Philosopher and the Microscope: Nicolas Hartsoeker Unravels Nature's “Admirable Œconomy”

Abstract

In a 1685 letter to his younger brother Christiaan, Constantijn Huygens wrote, "How can a garçon like him who hardly knows any mathematics and hasn't had a masterteacher [maistre] set himself up as the first master of everybody?" 1 The 'boy' in question was the twenty-nine-year-old Nicolas Hartsoeker 2 (1656-1727). Constantijn seemed indignant at the news that "the same Hartsoecker who taught us how to make the small bead lenses for microscopes" had now mastered the art of making very large telescope lenses. 3 There was more to Constantijn's sarcastic tone, however. From the letter exchange between the Huygens brothers, we learn that the young lens maker had been missing in action for a long time. Since September 1679, the brothers had not heard anything from him directly. And this after Huygens played a crucial role in taking Hartsoeker with him to Paris and introducing his younger compatriot to the French Academy of Sciences. 4 Aware of his brother's help in launching Hartsoeker's career, Constantijn seemed indignant about Hartsoeker's silence. "I beg you to write to Paris as soon as possible to find out all the details. You could even write to Hartsoeker himself, provided that he doesn't disdain corresponding with poor people like us", harrumphed Constantijn. "If his lenses are as perfect as they should be", he continued, "you will see that this man will soon be sought after by some great patron…". But how could a garçon like Hartsoeker have become "such a great [lens grinding] master on the sly"? 5 This is a striking remark from Constantijn, who in a letter to his brother Christiaan once called Hartsoeker "the inventor of our microscopes". 6 This episode reveals yet another key element here. Both Christiaan and Constantijn Huygens were avid lens grinders, who much of the time discussed techniques, instruments and new strategies in applied optics. Therefore, both were interested in lens-related novelties and gifted lens makers who were few and far between. Hartsoeker was one of these young and skilled lens makers.In this article, I explore Nicolas Hartsoeker's role as instrument maker and his use of materials and tools in launching his own natural philosophical programme. His lens grinding talents got the attention of Christiaan Huygens (1629-95) and Giovanni Domenico Cassini (1625-1712) at the Académie who invited him to work there. At the Parisian Academy, Hartsoeker supervised the production of glassware for all the scientific instruments destined for the Jesuit missionaries in Siam and India. 7 His skills earned him a job at the Academy's Observatory, for which he made telescopic lenses. 8 He ground lenses, invented new lens-making machines, conducted chymical experiments with burning mirrors, magnetized needles and metal bars, dissected