ABSTRACT
Engineers often recall their inventions. These recollections provide im portant narratives for the history of technology. Historians, however, are well aware that these recollections should not be taken literally. Engineers’ memories o f what happened, say, twenty years ago are not always exactly correct. They sometimes put too much emphasis on the novelties they introduced, while devaluing others’ contributions. Recollections may give the engineer a psychological satisfaction, or may provide an intellectual glue to hold the engineering community together, but they sometimes serve a more direct purpose. W hen the authorship’ o f a technology is at stake in a court, recalling how one invented, or made a contribution to the invention, the technology in dispute is an im portant strategy for patent litigation. In this case, the engineer may well stress radical differences o f his technology from that o f others. The engineer may also stress the origins o f that technology in his previous work, providing a smooth continuity between his past work and the later invention. The simultaneous existence o f discontinuity (from others’ work) and continuity (to his own work) frequently characterizes an engineer’s recollections on the invention of novel artifacts. 1
We can find a similar plot in John Ambrose Fleming’s recollection of the invention of the thermionic valve in 1904. In a series of well-known recollections, Fleming remembered that he transformed the Edison effect into the valve in 1904, when a sensitive signal detector was badly needed for wireless telegraphy. The Edison effect was a curious effect that Edison and his assistants discovered in the early 1880s inside a specially con structed light bulb. In 1889 Fleming performed a series of experiments on the Edison effect and conceptualized it in terms of unilateral conductivity in the vacuum inside the bulb. Some of the lamps that Fleming used in 1889 are shown in Figure 1 and Figure 2.
