Various methods of applying a pyrometer to common heat-treatment furnaces are shown in Figs. 120 to 122.
FIG. 116.—Eight-point recording pyrometer-Carpenter Steel Co.
LEEDS AND NORTHRUP OPTICAL PYROMETER
The principles of this very popular method of measuring temperature are sketched in Fig. 123.
FIG. 117.—Multiple-point thermocouple recorder—Bethlehem Steel Co.
FIG. 118.—Tycos pyrometer in oil-fired furnace.