Experimenting and Measuring Natural Powers: a Preliminary Study on Leonardo’S Ways to Quantify the Intensity of Percussion

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Experimenting And Measuring Natural Powers 35

Chapter 2 Experimenting and Measuring Natural Powers: a Preliminary Study on Leonardo’s Ways to Quantify the Intensity of Percussion

Andrea Bernardoni

1 Introduction1

Leonardo was a protagonist in the renewal attempt to develop a reform of physics, which was theoretical in the late fifteenth century, in order to trans- form it into a discipline applied to the construction of machines. Even though this audacious and bold attempt was doomed to failure, Leonardo’s empirical research remains extremely interesting and represents the high level of physics argumentation discussed in the cultural context of the Artes mechanicae. Leonardo conducted trials and built scientific instruments in order to measure the “powers of Nature” (potenze di natura)—force, motion, weight and percussion. Leonardo saw these “powers” as the foundation both of natural and arti- ficial phenomena and they are the basic principles for each technological process and his work on machines. This essay recognizes for the very first time Leonardo’s experimental process and the instruments he developed to ob- serve, quantify, and measure the power of percussion.

2 Mechanics in the Middle Ages

Two different traditions have to be taken into consideration in order to talk about mechanics during the Renaissance: on the one hand a long, consolidat- ed academic tradition based on the works of Aristotle and Archimedes and, on the other hand a “new course” of mechanical arts in which artisans and engineers construct machines, and mechanical processes using experience and intuition. The tradition of scholars essentially focused on the De ponderibus tradition, the classic “simple machines” (lever, inclined plane, wedge, screw and pul- ley) presented in the Aristotelian Mechanical Problems and developed during the twelfth century in the Elementia Jordani super demonstrationem ponderis.

1 Citations from Codex Atlanticus, Codex Arundel and Codex Foster II are produced by me.

Dynamics, especially the problems of velocity and acceleration, was studied in the theory of intensio and remissio formarum developed in a philosophical tradition from Oxford and Paris. Thomas Bradwardine, Richard Swineshead, William Heytesbury and John Dumbleton, in Merton College, developed math- ematical quantification and the description of motion, looking at velocity and acceleration from a geometrical point of view. While in the Sorbonne, university authors like Oresme, Johannes Buridanus, Alberto di Sassonia, focused on the problem of impetus: forces and motion studied from a dynamics perspec- tive.2 Outside of the academic scholastic tradition, in the artes mechanicae context, engineers dealt with empirical problems arising from the daily use of “simple machines” to lift or move weighty loads. Engineers learned and developed their knowledge based upon empirical practice. During the Middle Ages protagonists of this tradition worked anonymously; they were often illiterate and used writing and drawing only when these were required in their work. During the fifteenth century a deep epistemological renovation characterized the artes mechanicae cultural context. Artisans and engineers started making treatises on their professions and on machines. Gradually, from a curious ob- ject arousing marvel and astonishment, machines became objects of geometrical analysis focused on understanding and improving their efficiency.3 Leonardo is the main protagonist of the empirical aspect of improving mechanics. His manuscripts, largely dedicated to technology, physics and the science of nature, are a very singular and rare source. He is the only self-taught

2 Cfr. Marshall Claggett, The Science of Mechanics in the Middle Ages, (Madison: The University of Wisconsin Press, 1979), XXV-XXVI. 3 For a short bibliography of the cultural context of technology and its role in the history of science and technology, see Edgar Zilsel, Social Origins of Modern Science, eds. Diederick Raven, Wolfgang Krohn, and Robert S. Cohen (Dordrecht-Boston-London: Kluver Academic Publishers, 2000); Carlo Maccagni, “Leggere, scrivere e disegnare la “scienza volgare” nel Rinascimento,” in Annali della Scuola Normale Superiore di Pisa, (Pisa: Scuola normale superiore, 1993), 631–675; Paolo Galluzzi, “Le macchine senesi. Ricerca antiquaria, spirito d’innovazione e cultura del territorio,” in Prima di Leonardo. Cultura delle macchine a Siena nel Rinascimento, ed. Paolo Galluzzi (Milano: Electa, 1991), 15–44; Id. Mechanical marvels: in- vention in the age of Leonardo (Florence: Giunti, 1997); Id., “Portraits of Machines in Fifteenth Century Siena,” in Non-verbal communication in science prior to 1900, ed. Renato G. Mazzolini (Florence: Olschki, 1993), 53–90; Pamela Smith, The Body of the Artisan: Art and Experience in the Scientific Revolution (Chicago and London: University of Chicago Press, 2004); Robert Halleux, Le savoir de la main: savants et artisans dans l’Europe pré-industrielle (Paris: A. Colin, 2009), 102–139; Pamela Long, Artisan/Practitioners and the Rise of the New Sciences, 1400–1600 (Corvallis: Oregon State University press, 2011), 10–29; Andrea Bernardoni, “Artisanal Processes and Epistemological Debate in the Works of Leonardo da Vinci and Vannoccio Biringuccio,”, in Laboratories of art: alchemy and art technology from Antiquity to the 18th century, ed. Sven Dupré (Cham: Springer, 2014), 53–8.