Recently Dr. M. H. Hey published in this journal a method to construct graphically a projection showing the relation of two etched surfaces M and N to the crystallographic axes of a mass of the Gibeon meteoritic shower. Upon those faces could be distinguished the traces of four octahedron planes 0 l, 0 2, 0 3, 0 4 which are inclined at the following angles, measured clockwise from the intersection [MN] of the etched surfaces: on surface M 22°, 62°, 98°, and 135° and for the same octahedron planes on surface N 106°, 38°, 150°, and 86°, respectively.

The two faces M and N are at an angle of 84° one to the other. Hey's solution of the problem is based on a reversal of the Goldschmidt construction for drawing crystals from the gnomonic projection.