Pyrometers

A non-contact temperature measuring device, typically used to measure temperatures of glowing hot metals in a steel mill or foundry. Also known as an Optical Pyrometer.

To measure the temperature of incandescent metals, you look through the pyrometer at the glowing metal, and turn a knob or ring which adjusts the temperature of a glowing filament projected into your field of view. When the color of the filament matches the color of the metal, you can read the temperature from a scale on the filament color adjusting knob/ring.