Mortise

The oak beam lay across the bench, and Nyra had chalked a small square on its face where the hollow would go. The girl watched her set the chisel inside the line and tap it once, lifting a clean chip of wood. A mortise is a measured emptiness, cut to receive the tongue of another timber, and a beam is only as sound as the hollow it is given.

“Why cut a hole at all,” the girl asked, “when you could lay one piece on the other and nail it fast?”

“A nail holds by biting,” Nyra said, “and a bite can be worked loose. A mortise holds by fitting. The tenon slides into the dark of it and the two pieces become one piece, so that a pull on the beam is a pull on the whole joint and not on any single tooth.” She pared the walls square and true, checking the depth against a scored stick, and the hollow deepened into the grain.

When the tenon was shaped she eased it in, and it seated with a soft knock and would not rock. Then she drove a single wooden pin down through both pieces where a bored hole crossed the joint. “The pin is the last word,” Nyra said. “It draws the shoulder home and keeps the tenon from ever backing out. You could write the depth of this mortise in a ledger to the width of a hair, and the number would be true, and it would not tell you the moment the pin pulled the joint tight under your hand.”

A book gathers what can be set down in a line and counted, and leaves the rest to the one who was there. It can keep the square you chalked and the depth you scored, but not the small settling knock of a tenon finding its seat, nor the weight of the mallet in the last blow. The book keeps the depth, and you keep the pinning of it.