Several recent studies in science and technology studies (STS), and in the history of science and technology, have highlighted the stochastic and uncontrollable nature of technological trajectory. In this paper I will examine three technologies--the Triode, the numerically controlled (NC) machine tool, and the Internet--each of which reflects a different aspect of technological uncertainty. I will argue that the Triode's seemingly unpredictable evolution is partly caused by limitations in our present historical knowledge about it. The NC machine's mysteriously unpredictable life emerged partly from the unpredictability in the conflict between workers and managers, and partly from historians' blurring the boundary between workers and managers, combining them into one general category--humans--and contrasting humans with machines. Finally, I will show that the Internet's tremendous momentum should not be interpreted as showing technology's autonomous life, since American engineers constantly intervened in its course through public shows and through the negotiation for international standardization procedures. On this basis, I will also critically examine the cultural meaning of autonomous technology including the constructivist discourses of nonhuman agency.