A ``double‐clamshell'' arc image furnace system has been successfully utilized in a practical arrangement for the measurement of thermal expansion and electrical conductivity under a controlled atmosphere. Maximum sample temperature of 2138°K has been achieved by using two 5000 W xenon arc lamps as energy sources. At 1500°K, a temperature gradient of 6°K/cm was measured along the furnace axis by thermocouples shielded with alumina, but without a sample in position. The thermal conductivity of a sample would reduce the gradient to less than 1°K/cm.