PATTERNS OF TRANSFORMATION IN SEVENTEENTH-CENTURY MECHANICS' Introduction The seventeenth century witnessed striking transformations in the science of mechanics: whereas Renaissance authors of the previous century were primarily concemed with restoring and extending the achievements

The seventeenth century witnessed striking transformations in the science of mechanics: whereas Renaissance authors of the previous century were primarily concemed with restoring and extending the achievements of Antiquity, following largely in the same track, seventeenth-century practitioners brought meehanics to radically new domains, such as the mathematical investigation of motion in its many manifestations. I have recently argued that the objects or devices employed in the seventeenth century are a key tool for documenting and investigating such transformations in a way that reflects the contemporary practice of mathematicians and natural philosophers: levers, inclined planes, pendulums, springs, and strings were employed in a variety of fashions, both practical and theoretical, to open new areas of research and conceptualize difficult problems.2 In this essay I wish to extend and refine my earlier reflections by identifying some pattems of transformation in this extraordinarily rich and complex area, studying similarities and differences in the creative and original methods employed by practitioners in exploring new domains. Such pattems are potentially fertile territory for bridging historical and philosophical themes having to do with research practices on the one hand, and methodological and cognitive aspects on the other.3 I have identified three types of transformations. My first set of examples can be characterized as "unmasking," namely the reeognition that apparently complex and elaborate objects or deviees can be shown to consist of simple, known ones in disguise, as in a metaphorical removal of a veil or a mask. In these cases simple visual inspection—at times with minimalist interventions—enabled the reduction of several seemingly intractable cases to established ones. The term "unmasking" captures the minimal intervention required in these cases.