Antony van Leeuwenhoek's microscopes and other scientific instruments: new information from the Delft archives.

This paper discusses the scientific instruments made and used by the microscopist Antony van Leeuwenhoek (1632-1723). The immediate cause of our study was the discovery of an overlooked document from the Delft archive: an inventory of the possessions that were left in 1745 after the death of Leeuwenhoek's daughter Maria. This list sums up which tools and scientific instruments Leeuwenhoek possessed at the end of his life, including his famous microscopes. This information, combined with the results of earlier historical research, gives us new insights about the way Leeuwenhoek began his lens grinding and how eventually he made his best lenses. It also teaches us more about Leeuwenhoek's work as a surveyor and a wine gauger. A further investigation of the 1747 sale of Leeuwenhoek's 531 single lens microscopes has not only led us to the identification of nearly all buyers, but also has provided us with some explanation about why only a dozen of this large number of microscopes has survived.

'Most rare workmen': optical practitioners in early seventeenth-century Delft.

A special interest in optics among various seventeenth-century painters living in the Dutch city of Delft has intrigued historians, including art historians, for a long time. Equally, the impressive career of the Delft microscopist Antoni van Leeuwenhoek has been studied by many historians of science. However, it has never been investigated who, at that time, had access to the mathematical and optical knowledge necessary for the impressive achievements of these Delft practitioners. We have tried to gain insight into Delft as a 'node' of optical knowledge by following the careers of three minor local figures in early seventeenth-century Delft. We argue that through their work, products, discussions in the vernacular and exchange of skills, rather than via learned publications, these practitioners constituted a foundation on which the later scientific and artistic achievements of other Delft citizens were built. Our Delft case demonstrates that these practitioners were not simple and isolated craftsmen; rather they were crucial components in a network of scholars, savants, painters and rich virtuosi. Decades before Vermeer made his masterworks, or Van Leeuwenhoek started his famous microscopic investigations, the intellectual atmosphere and artisanal knowledge in this city centred on optical topics.

An eighteenth-century medical-meteorological society in the Netherlands: an investigation of early organization, instrumentation and quantification. Part 2.

Scholarship has offered a range of judgements of the Correspondentie Sociëteit. In their recent study of the Netherlands at the start of the nineteenth century, Joost Kloek and Wijnand Mijnhardt characterize the efforts of the Correspondentie Sociëteit as a 'temporary milestone' in 'medical involvement with society'. According to them, this involvement arose after 1750, after university-trained medical doctors had reoriented themselves towards empiricism as a working method. They claim that this resulted in a preventative medical programme starting in about 1770; this process made a significant contribution to increased professional feeling and professional respect of the medical class. Far more negative in his assessment was Harry Snelders, who in 1981 conducted a general investigation of the Verhandelingen of the Correspondentie Sociëteit. He concluded that 'in the end the Sociëteit left us with little more than many particulars about the number of births and deaths in many places in the country, which illnesses people died from, some meteorological observations and an overview of the many contributors'. Also rather negative in his judgement was Frank Huisman, who in 1997 investigated the medical records of the Groningen section of the Correspondentie Sociëteit. Although Huisman underlined the importance of the Correspondentie Sociëteit in the process of the emancipation of the medical class, he also concluded that in the medical field scarcely any insight had been obtained into dominant illnesses. According to Huisman, the medical publications of the Correspondentie Sociëteit 'do not contain an expected level of abstraction, on the contrary they were very casuistic and contained many lists without any form of interpretation'. He judged that the medical doctors of the Correspondentie Sociëteit were no more than 'defective empiricists', because they never explicitly explained the transition from empirical material to theory. In Huisman's opinion, 'the correctness of the ideas adopted was indisputable, so that measurements could never have led to a modification, let alone a rejection, of the theory'. The question arises as to whether this is a useful way of making historical judgements. From a historical viewpoint, processes and efforts rather than results are most important, and innovations with respect to the institution's contemporary practices are to be assessed. If the Correspondentie Sociëteit is examined from such a perspective, then the result is rather positive, at least for the society's meteorological aspect. In the meteorological section of the Verhandelingen attention was mostly devoted to the set-up, methodology and recording of observations. This is hardly surprising, because in this field organized and systematic work was something very new in the Netherlands; members of the Correspondentie Sociëteit had to discover this effectively at first hand. There was no previous expertise on which to rely. The Correspondentie Sociëteit was the first in the Netherlands to genuinely organize scientific research. Moreover, contributors to the society performed much work. During a period of just over ten years the society published eleven volumes with almost five thousand pages of printed observations, about one-third of which was concerned with meteorology. Although these volumes were indeed partly descriptive, this does not mean that a higher level of abstraction was not the aim. For example, in his report about the weather during the years from 1779 to 1781, Van der Weyde sought to draw thoroughly analytical conclusions and even provided methodological arguments. According to Van der Weyde, the body of knowledge formed 'one large structure' which would only progress when many investigators worked on it together. Various types of natural knowledge needed to be distinguished. Meteorological knowledge could only be deduced from observation. Van der Weyde held that reliable natural knowledge was generated in three stages: first, collection and description of the phenomena; then the more difficult step of deriving inferences or patterns from these observations; the third step, the most difficult, to find an underlying theory or explanation. This step could only be taken after much preliminary work had been done. Van der Weyde considered Van Swinden's work on the magnetic needle to be an example of the first phase, that of describing phenomena. An example of the second phase, the derivation of inferences, was

An eighteenth-century medical-meteorological society in the Netherlands: an investigation of early organization, instrumentation and quantification. Part 1.

In many areas of the eighteenth century was a starting point for the quantification of science. It was a period in which the mania for collecting led to the first attempts in systematization and classification. This penchant for collecting was not limited to natural history specimens or curiosities. Due in part to the development of mathematical and physical instruments, which became more widely available, scholars were confronted with the informative value of numbers. On the one hand, sequences of measurements appeared to be the key to the advancement of scientific knowledge, yet on the other hand the mathematical apparatus to deal with these data was still largely lacking. As a result of this the first meteorological networks organized in the eighteenth century all became bogged down in the large amount of information that was collected but could not be processed properly. This development is illustrated in a case study of an early Dutch meteorological society, the Natuur-en Geneeskundige Correspondentie Sociëteit (1779-1802). What were the factors that triggered this interest in the weather in the Netherlands? What were the goals and expectations of the contributors? What were their methodological strategies? Which instruments were used to measure which meteorological parameters? How was the stream of numbers generated by these measurements organized, collected and interpreted? An analysis of this process reveals that limits on the advancement of meteorology were not only imposed by eighteenth-century Dutch Republic and the lack of a proper theoretical insight were also crucial factors that eventually frustrated the breakthrough of meteorology as an academic science in the Netherlands. This breakthrough was only achieved in the second half of the nineteenth century.

"A bare outpost of learned European culture on the edge of the jungles of Java": Johan Maurits Mohr (1716-1775) and the emergence of instrumental and institutional science in Dutch colonial Indonesia.

The transits of Venus in 1761 and 1769 appear to mark the starting point of instrumental science in the Dutch East Indies (now Indonesia). This essay examines the conditions that triggered and constituted instrumental and institutional science on Indonesian soil in the late eighteenth century. In 1765 the Reverend J. M. Mohr, whose wife had received a large inheritance, undertook to build a fully equipped private observatory in Batavia (now Jakarta). There he made several major astronomical and meteorological observations. Mohr's initiative inspired other Europeans living on Java around 1770 to start a scientific movement. Because of the lack of governmental and other support, it was not until 1778 that this offspring of the Dutch-Indonesian Enlightenment became a reality. The Bataviaasch Genootschap van Kunsten en Wetenschappen tried from the beginning to put into effect the program Mohr had outlined. The members even bought his instruments from his widow, intending to continue his measurements. For a number of reasons, however, this instrumental program was more than the society could support. Around 1790 instrumental science in the former Dutch East Indies came to a standstill, not to be resumed for several decades.