thermophone

n. [ Thermo- + phone. ] 1. A portable form of telethermometer, using a telephone in connection with a differential thermometer. [ Webster 1913 Suppl. ]

2. A telephone involving heat effects, as changes in temperature (hence in length) due to pulsations of the line current in a fine wire connected with the receiver diaphragm. [ Webster 1913 Suppl. ]