A telemetry system that measures temperatures within a burning coal seam from beneath the seam is described. The temperature data are laterally transmitted through the earth to a receiver outside the high-temperature zone and then sent to the surface by wire. The system has a range of 46 m, battery capacity for 6-months operation, and performs 12 external measurements each hour. Complete electrical schematics together with ordering instructions for the fabrication drawing set are included in this report.