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Published online by Cambridge University Press: 14 March 2018
Consider the poles of the faces of a crystal and the zones (great circles) which join them. Suppose we have given their gnomonic projection on to a certain tangent-plane to the fundamental sphere on which these poles and zones lie. We can find the gnomonic projection on any other plane by aid of the gnomonic net, as explained in this Magazine (1904, vol. xiv, p. 19); and similarly for the stereographic or orthographic projection.
page 244 note 1 For a face-pole is the intersection of two zones, &c. V. Goldschmidt gave a method of finding the directions of the new projections in Zeits. Kryst. Min., 1891, vol. xix, p. 852Google Scholar. See also J. W. Evans, this Magazine, 1906, voi. xiv, p. 151.
page 246 note 1 That is, the picture of the crystal as seen by an eye at a considerable distance in the normal to the plane.
page 246 note 2 The directions of the new projections of the zones are sufficient for drawing the picture of the crystal. See Goldachmidt, loc. cit.
