Electric Arc Furnace: the Héroult Series-Arc Steel Furnace (Stansfield, 1914)

Héroult's steel furnace: a tilting hearth like an open-hearth furnace, lined with dolomite, with two carbon electrodes coming down through the roof. The current goes down one electrode, arcs into the slag, passes through the molten steel and arcs back up the other, so the heat goes straight into the metal. Result: an electric steel furnace about 7 x 4 ft inside for a 3 ton charge, run at about 350 kW and 110 V. Source: A. Stansfield, The Electric Furnace, 2nd ed. (1914), pp. 115-116, 214-216. Unknown: case and tilting gear details, electrode size. Picture: a drawn diagram (Fig. 93 is blank in the scan).