Dr. Nagy I. Zoltán szerk.: Fragmenta Mineralogica Et Palaentologica 4. 1973. (Budapest, 1973)

these results not only by design but by compution, too. The al°;orhythm of the vector-geometrical compution is summarized as follows : The crystal-morphological and optical vibration directions measured by the U-table were considered to be the unit vector starting from the origo of a right-angular rightward rotating system of co-ordinates. The X and Y axes of this system of coordinates lie in the plane of the slide, the Z axis is the normal of this plane. The X axis coincides with the H axis of the U-table, its positive part is directed towards us. The positive part of the Y axis lies in the right,that of the Z axis is above the slide's plane. The n and h values measured by the U-table determine unambiguously the spatial position of the vector but these should be converted into vector components. First the | and tj values can be determined. The following relation is valid when the h-values are read by inclining the table rightwards. The geometrical sense of % is the- following: when drewing a perpendicular from the end-point of the vector on the XY plane and this will be connected to the origo than the straight includes an angle of Ç with the positive part of the X axis. This angle is measured by left-handed rotating from +X towards the projection of the vector. y) is the angle included by the vector and the XY plane, above the XY plane it is positive, below that it is negative. The designation Ç and ») is equal to that given by C. Burri (Anwendung der Vektorrechnung auf einige häufig auftretende kristalloptische Probleme, p. 267). To compute the vector components also the equations of C. Burri are used: 0 = n + 90° = COS r] COS ç = COS ç , V = sin y] X z