Explains the principles underlying all devices used to sense temperature, and how the sensor signals are processed to convert them to indications of temperature. Describes the fundamental concepts of temperature, the Thermodynamic Temperature Scale, and the International Practical Temperature Scale. Covers sensor choice, response characteristics, heat transfer conditions, installation errors, instrumentation compromises, and mechanisms of sensor deterioration. Many specific sensors are described, including expansion devices, liquid-in-glass thermometers, electrical resistance devices, thermistors, electronic sensors, thermocouples, disappearing filament optical pyrometers, infrared pyrometers, total radiation pyrometers, pyrometric cones, and other novel methods. Includes discussion of measurement of temperatures to a fraction of a degree Kelvin.