5 is not operated on line as shown but in line the housing 32 can also be formed by an extension of the casing of the preceding dryer section of the paper machine the housing 32 also is provided with a steam generator 40 shown diagrammatically which blows steam into the interior of the housing 32 through three feed nozzles 41 42 43 the housing 32 thus also serves as a steam humidifier the sheet material 3 passing through the housing 32 is thus exposed not only to the pressure and temperature in the roller gaps of the roller stacks 6 7 but also to the correspondingly higher temperature and humidity of the atmosphere within the housing 32 the moisture content of the sheet material can be measured by measuring equipment 44 which is connected with and controls the steam generator 40 this results in a closed control loop for controlling the moisture content of the sheet material the interior of the housing 32 is connected through a pipeline 45 with the interior of the chamber 22 in which conveying apparatus 46 may optionally be provided transport of atmosphere from the treatment station 5 into the chamber 22 is provided through pipeline 45 in this manner the energy emitted by the heated rollers 8 9 can also be utilized for heating the chamber 22 if the steam generator 40 appropriately humidifies the atmosphere in the housing 32 this humidity can also be transferred into chamber 22 a roll 2 of sheet material is deposited for example with the help of a crane or a lifting vehicle on the first storage space 16 of the roll magazine 15 whenever a roll 2 has been unwound in.