In a recently published paper (J. Inst. Elec. Eng., 93, Part 2 No. 34, Aug. 1946), Messrs. F. W. Tomlinson and H. iscuss the development and uses Brconductors employing as insulating compressed magnesium oxide powder. Irr consequent of the high-temperature stability and the good insulating properties of this material, these conductors have found wide application as electrical heating elements in radiant boiler-plates and as power supply cables in circumstances where the avoidance of fire-risk is of special importance, or where the ambient temperature or atmospheric conditions are too severe for other types of electric cable. The low dielectric loss exhibited by magnesium oxide at very high frequencies, combined with the other advantageous characteristics mentioned, has also enabled specially designed cables to be used for certain, important radar purposes.