Abstract: Method and device in a head box of a paper machine for controlling distribution of fiber orientation in a paper web in a transverse direction of the machine. In the method, the transverse speed component of a discharge jet is controlled by regulating alignment of turbulence pipes in a pipe battery of a turbulence generator in the head box. In the device of the invention, a perforated plate in the turbulence generator is provided with a heating arrangement, by which the temperature level of the perforated plate and thereby the length thereof and angle of alignment of the turbulence pipes attached to the perforated plate, in relation to the machine direction, can be controlled. The perforated plate is supported, at both opposite ends thereof, on vertical side walls of the head box, by fittings which permit thermal expansion and contraction of the perforated plate.