Abstract: A temperature measuring probe and method of detecting infrared radiation from flue walls and transmitting the detected infrared radiation through fiber optic cables to photoelectric detection-conversion cells which convert the radiation to electrical signals which are measured and translated into temperatures. Concentric metallic flexible hose mounted on a carriage for mobility provides water cooling for the fiber optic cable with a portable reeling machine for controlling the movement of the cable, hose, and probe head. The probe head provides viewing ports for the terminal ends of the fiber optic cable.