When data were being gathered in 1961 for National Bureau of Standards Monograph 40 [3] on Thermocouple Materials, a section was included to cover ceramic packed thermocouple stock "because of the wide use and increasing popularity." New uses continue to be found for this unique hetrogeneous materials combination. Compacted ceramic insulated thermocouple material consists of three parts as shown in Fig. 21. The advantages of this configuration are: 1. It isolates the thermocouple wires from environments that may cause rapid deterioration. 2. It reduces long term calibration drift. 3. It lessens temperature versus wire size problems. 4. It provides an excellent high temperature insulation for thermocouple wires. 5. The sheath can be made of a metal compatible with the process in which it is being used and bears the brunt of the environmental effects. 6. It is easy to use: a. Forms easily and retains the bent configuration. b. The sheath can be welded without loss of insulation. c. Available in a wide variety of sizes and materials. d. Readily fabricated into finished thermocouple assemblies with minimum of technique and equipment. e. Useful at high pressures or high temperatures or both. 7. It is inexpensive as a finished thermocouple.