change of the reference value of the withdrawal speed strives to again adjust the original reference value the feedback unit 43 compares the value delivered by the output stage 44 with the reference value of the reference value adjustment means 29 and in the presence of deviations strives to again maintain the desired reference value with a certain time delay through direct action upon the output stage 44 during control of the bath level 35 with the aid of the metal inflow regulation circuit as well as the strand withdrawal regulation circuit owing to a change of the adjustment magnitude at the inflow regulation circuit which exceeds a certain value per unit of time the favorable prescribed withdrawal speed for the casting operation is increased or reduced after the bath level 35 has again reached its prescribed reference value the feedback unit 43 at the function transmitter 28 insures that the withdrawal speed is changed for such length of time until it again reaches the value most favorable for the casting operation this change in the withdrawal speed brings about a deviation of the bath level 35 in the positive or negative direction which is then recorded by the measurement device or mechanism 11 these changes are however only of such magnitude per unit of time that only the inflow regulation or control circuit responds thereto as a result the.