Can a scientific instrument be regarded as a failure? Why and how? By shedding light on the complexity of these questions, the volume marks a step forward in the way historical scientific instruments can be analysed and displayed. The essays show how diverse failures can be, and how the assessment of scientific devices may change over time — some surprisingly becoming more successful. In addition to studies of how technical features led to failure, the authors examine the roles played by social bias and behaviour, commercial and economic circumstances, and political factors.