This essay is a contribution to the history of methodological thought. I focus on key methodological criteria for successful experimentation, replication and multiple determinations of empirical evidence. Drawing on reports of experiments with viper venom from the late seventeenth and late eighteenth centuries, as well as on present-day methodological thought I examine whether past experimenters regarded repetition, replication, and multiple determinations as criteria for validity; what exactly they meant by this; what they hoped to gain by repeating, varying, triangulating, and (...) replicating; and how relevant these criteria were for them. I also consider if this analysis has implications for current philosophical work on the methodology of experimental practice. (shrink)