A method is given for determining the lattice parameter along the Weissenberg rotation axis, for non-triclinic crystals. The lattice constant is derived for each layer from the equi-inclination formula, the $\mu$ angle being precisely settled on the basis of the deviations from linearity of the «central» lattice lines. Besides, a method for enhancing the misalignment of the crystal is given, which uses oscillation photographs of the highest recordable layer line. In this way it is possible to measure practically the double of the tilt angle.