5 in accordance with the invention onto the following guide roll 62 and further using a device 35 6 in accordance with the invention via a measurement device 73 and a guide roll 74 to the reel up 70 by means of two devices 35 7 35 8 of the invention placed underneath a movable air blow plate 77 is placed after the measurement device 73 for conveying the lead in strip in connection with which plate a pneumatic cylinder 77 a is provided for displacing the plate 77 in the machine direction as the figure shows the devices 35 1 to 35 8 in accordance with the invention can be placed above or under the lead in strip and provided with movable air blow plates at scanners through passages etc fig6 schematically shows an embodiment example in which a lead in strip is passed from the last drying cylinder 51 of a dryer section 50 directly through measurement devices 81 73 to a reel up 70 as fig6 shows devices 35 in accordance with the invention are placed in all suitable open draws over which the lead in strip is passed the devices in accordance with the invention are numbered consecutively using a subscript 35 1 to 35 6 guide rolls are designated by the reference numerals 52 82 83 74 fig7 shows an embodiment example in which devices 35 1 in accordance with the invention are used in a draw between a dryer section 70 and a measurement frame 95 the lead in strip is passed to a size press 90 and to an after dryer section 79 by rope threading fig8 schematically shows pressures as compared.