The use of clocks for timekeeping seems to be a straightforward and almost intuitive routine. Yet glancing at mechanical clocks designed in a culture remote from us in both time and space we witness how modern-day intuitions betray our attempts to understand these time-measuring devices. This confusion arises because “time” itself is far from being obvious but rather comprised of numerous assumptions, deeply rooted in cultural habits of dealing with time-keeping technology. In my project I investigate the array of technological, conceptual, visual and computational habits underlying the notion of time by following the case study of timekeeping in Edo period (1600-1868) Japan.
When mechanical timekeeping technology was introduced to Japan from the West in the sixteenth century it underwent a metamorphosis adapting to the Japanese time system, in which hours changed their length with the seasons; yet in the mid nineteenth century Japanese scholars wholly accepted the Western conventional notion of time as a universal and abstract entity independent of human activity. What were the forces behind this transformation? How did Japanese scholars come to accept Western notion of time without ever being explicitly told what is was? In order to answer these questions I look at the changing timekeeping practices of Japanese astronomers. Time-measurement was an essential feature of any astronomical practice, yet the kind of “time” used by various Japanese astronomers changed throughout the eighteenth and the nineteenth century, stimulating major transformations in the field of Japanese astronomy, and following that, in geography and navigation. Looking at particular astronomical practices I trace the changes in the notion of time to the specific habits employed by astronomers — habits rooted in mathematical calculations, habits of handling mechanical devices, habits of visual depiction, and linguistic and conceptual habits that guided nineteenth century Japanese readers of Western nautical texts. My goal in this project is to show how by adopting Western practices that corresponded with Western notion of time, Japanese scholars came to posses an array of implicit and disperse pieces of the puzzle that comprised that notion. Examining the habits that were the pieces of that puzzle, I follow the conceptual path Japanese scholars took to reconstruct and accept the characteristics of Western notion of time.