This book attempts to look inside boilers, beyond the pressure switches that cycle a boiler on and off, and into the many factors such as types of boilers, methods of construction, Code requirements, fuels, firing, programs of operation, safety controls, safety devices, possible causes of malfunction, methods of repair, maintenance, feed water treatment, state laws, and the many other features that can affect a boiler, and the operator or owner-user involved with boilers, in his daily business. Salient Features This volume is arranged in question and answer form, it is not limited to typical standard questions and answers geared only to pass operator license examinations. The stress is on fundamentals, and where need be, it goes beyond these to help the reader grasp the meaning and depth of a lead question. This volume should prove beneficial to the smaller plants with no licensed or trained operators and it should certainly help those plants where operators need a review of boilers prior to taking an examination or need training as operators. Management people should find this material helpful in assessing their current practices on boiler maintenance and operation and also in ful-filling their obligation to provide a safe and legal boiler plant. Stationary license examiners will find this volume useful in preparing examinations, thus helping to bring the standard of operating engineers up to a uniform level.