Hints for Crystal Drawing

Abstract

THE importance of accurate drawings of crystals in any crystallographical discussion was recognised by Haüy, the father of crystallography, but the principles upon which such drawings should be made were not clearly explained until the publication by Haidinger of his well-known paper among the memoirs of the Wernerian Societv many years later. It is essential that edges which are parallel on the crystal should be represented by parallel lines on the drawing, a condition which entails the supposition that the eye views the crystal from an infinite distance. Consequently, in such a special case as a skeletal cube in which the edges are drawn of equal thickness, the eye would be puzzled as to which is the front, and the cube would appear constantly to be turning inside out; but, as a rule, no such ambiguity would arise. It is also important that the directions of the edges in the drawing should be determined with mathematical precision, even when the crystal is shown in perspective.