The Thirty-two Classes of Crystal Symmetry

Abstract

THE fact that crystals may be classed according to their symmetry into thirty-two different classes is widely known, but there are very few who could enumerate all these classes, or state the exact symmetry that each possesses. They are not, as a rule, arranged on any intelligible principle, nor are the various names they have received generally self-explanatory or easy to remember. It has been proposed, indeed, to refer to them by consecutive numbers, like the omnibuses of the London streets, but this is a counsel of despair.