Torching 5 : The application of mortar to the underside of slates and tiles on a roof. Toroidal coil. A winding taken round an iron ring. When the current flows in the winding, a magnetic circuit is set up in the iron core
H. J. Porter (Chairman - Technical Committee), Dictionary of Fire Technology, The Institution of Fire Engineers, The Victory Press (Leicester) Ltd. 1979 UK. (Fr Tech - Brit) {81}