transmission between them such an ideal course of the draft of drafting means 15 is not possible with the prior controls in fact the draft of the drafting means 15 changes in the known control of fig3 in accordance with the solid line thus the actual course of the draft of the drafting means 15 cannot follow the desired ideal course rather an error occurs which is designated in fig3 by the shaded area f the size of the area f corresponds to the magnitude of the error when the device is operated according to known control methods in fig4 which generally corresponds to fig3 the course of the draft of the drafting means 15 of the device of fig1 is shown which illustrates operating according to the method and means of the present invention in the control used in this fig4 a delay time t 39 is provided which extends from time t1 of the measured variation in mass to a time t4 time t4 results from the travel time tl minus a correction time dt the travel time tl extends as already explained from time t1 to time t3 the correction time dt is determined by the calculator 25 as a function of the magnitude and or rate of the variation in mass sensed at time t1 the correction time dt is a time by which the travel time tl is shortened thus.