It is a great defect in most school courses of geometry that they are entirely confined to two dimensions. Even if solid geometry in the usual sense is not attempted, every occasion should be taken to liberate boys' minds from what becomes the tyranny of paper But beyond this it should be possible, if the earlier stages of the plane geometry work are rapidly and effectively dealt with as he1e suggested, to find time for a short course of solid geometry. Euclid's eleventh book is generally found dull and difficult, but all that is of real value in it can be dealt with much more rapidly, especially if full use is made of the idea of the motion of a line or of a plane. Similarly it should be found possible to include a study of the solid figures; this will be much facilitated if their general outlines have been made familiar at the very commence ment as is usually the case.