Chapter 5 Mathematical Instruments Changing Hands at World’s Fairs, 1851–1904 Peggy Aldrich Kidwell From the 1851 Crystal Palace exhibition in London to the 1904 Louisiana Purchase Centennial Exposition in St. Louis, Missouri, world’s fairs were places where mathematical instruments changed hands. Mathematicians, inventors and entrepreneurs sought customers for their innovations and the recognition of international panels of judges. The instruments on display included early commercial adding and calculating machines, pioneering difference engines, newly designed slide rules, and sophisticated geometric models. Vendors also sold traditional drawing instruments like protractors and rules, often manu- factured using new materials and production techniques that greatly reduced cost. These appealed to a broad range of potential customers, including math- ematicians, engineers, and scientists. Exhibits at fairs not only contributed to the spread of ideas and products, but were used by governments to demon- strate the modernity and intellectual achievements of nations. Both the math- ematical community and people represented at the fairs came to include a much larger portion of the world. Surviving objects, printed documents, and archival materials amply demonstrate the improvement, diffusion, and inter- nationalization of the material culture of mathematics as it occurred through exhibition at the fairs. A few of the objects shown in the period 1815–1904 illustrate the role of fairs in shaping the exchange of instruments and ideas. As a list of important fairs indicates (Table 5.1), the events were held most frequently in London and Paris, with occasional forays elsewhere in Europe and to the United States. Several things happened—or sometimes happened—to mathematical instruments shown at these expositions. First, they were displayed. A local committee decided the general classification of exhibits and allotment of space. Within this scheme, particular exhibits were designed by the exhibi- tors, be they individuals, organizations, or government bodies. Decisions about ‘who exhibited what’ depended on local, national, and international politics as well as the novelty and quality of inventions. Second, the mathematical objects shown were publicized. Exhibitors pub- lished books and brochures and arranged demonstrations. Local, national, and © koninklijke brill nv, leiden, ���7 | doi ��.��63/97890043�4930_006 Mathematical Instruments Changing Hands 89 Table 5.1 Important World’s Fairs, 1851–1904 1851 London Great Exhibition of the Works of Industry of All Nations (Crystal Palace) 1853–1854 New York City Exhibition of the Industry of All Nations 1855 Paris Exposition universelle 1862 London International Exhibition of 1862 1867 Paris Exposition universelle 1873 Vienna Weltausstellung 1876 Philadelphia United States Centennial International Exposition 1878 Paris Exposition universelle 1885 London International Exhibition of Inventions 1889 Paris Exposition universelle de 1889 1893 Chicago World’s Columbian Exposition 1900 Paris Exposition universelle de 1900 1904 St. Louis Louisiana Purchase Centennial Exposition international press reports appeared. Official fair publications offered descrip- tions. Voluminous records of publications survive and are increasingly avail- able to scholars in electronic form. Third, entries were judged by an international panel of experts—preferably experts who had examined the displays, seen the literature, and witnessed the demonstrations. The judges might grant an award, which could be mentioned in later advertising. Fourth—in many cases—instruments changed hands. They sometimes were purchased by enthusiastic visitors. They occasionally were collected on the spot as specimens, most often by government agencies. Even those instru- ments that did not change hands at the fairs often were later collected as a result of publicity they had received. Finally, to a considerable degree, instru- ments exhibited at fairs have been preserved long past their use in mathemat- ics, science, and engineering. Objects which have found their way into the collections of the Science Museum in London, the Smithsonian Institution in Washington, D.C., and the Conservatoire National des Arts et Métiers in Paris, well illustrate this point. The connection of these objects to fairs has not always been well known. In other words, one fruitful question historians can ask about mathematical instruments from this time period is: What tie might there be between this object and a world’s fair? Some inventors were spurred .