Abstract: A furnace for the melting of glass in which horizontally spaced regions of the molten glass body are heated by passage of alternating electric current between diagonally opposed electrodes of two groups and supplied from a primary power supply circuit, and in an intervening zone above a withdrawal path leading to an outlet auxiliary electrodes spaced apart longitudinally of the zone are fed with current from an auxiliary supply circuit including regulators providing for adjustment of the heating effect along different parts of the zone to set up a convective effect balancing any downward pull which could draw unrefined glass or batch material into the withdrawal path.