Most of the school slates used in Great Britain come from Bangor, in North Wales, and are cut and faced by machinery. To make a single slate, get a Welsh roofing slate, and mark off with chalk to the size wanted. With any sharp point prick a number of holes about lin. from the chalk mark, and break off the useless portion. Lay the slate flat on a board and make the chalk mark coincide with the edge of the board. The slate may be cut to size with the edge of a half-round file, a heavy knife, a trowel, or with a joiner's tenon saw. To put a writing face on the slate it is polished in the following way. Select a slate as smooth as possible, fix it on a bench, and rub with a piece of soft sandstone, using sharp sand and water. Finish with a block of wood and finer sand, moving the rubbers with a circular motion. Or, instead, the face of the slate may be smoothed on a grindstone.