the supply roll 50 equipped with a delivery driving mechanism at centre not shown the web 4 is passed over a driven deflection roller 52 under a jockey roller 54 and some guide rollers 56 in a flat spreading device 58 the guide rollers 56 are arranged in an arcuate path the jockey roller 54 produces in a manner which is known to the man skilled in the art a signal to control the delivery motor not shown on the roll 50 the air spreader 58 acts by directed air jets on both sides on the knit fabric web 4 in such a manner that it leaves the spreading device 58 in an even smooth and wrinkle free condition and only little curls in the edges this spreading device may be adjusted on its pivotable support 60 as to its angle with the web 4 the knit fabric web is now passed on the lath roll 62 which is driven and whereon the material web is further centred and better spread the lath roll 62 and the air spreading device 58 are known and commercialized products of the company erhardt amp leimer kg augsburg federal germany the man skilled in the art is familiar with construction and the function of these machine elements the web now centred passes on a free running guide roller 64 in a device 65 for the contactless measuring of the weight per unit area and then through a second air spreading device 66 which is constructed like the first spreading device 58 on the counter roll 6 which is positively.