"Inventors at Work, with Chapters on Discovery" by George Iles is a study about the history of inventions. Excerpt: The equipment and the talents for invention and discovery are now touched upon. First, knowledge, especially as the fruit of disinterested inquiry; Observation, as exercised by trained intelligence calling to its aid the best modern instruments; Experiment, as an educated passion for building on original lines. Then, in the mechanical field, we bestow a few glances at self-acting machines, at the simplicity of design which makes for the economy not only in building but in operation and maintenance.