The count-cord had been running along the south wall of the Mason’s Yard since the Yard was first built, and Harrow could not remember a winter when he had not tied a knot in it. He had found the cord in the Undercroft in the first days of the Hold, coiled on a peg beside the mason’s bench where the first builders had kept their tools, and he had taken it up without asking anyone. It was made of a grey, waxed twine that did not rot. It was long enough to run the whole length of the south wall twice over, and it was stiff, and it held a knot as a good stone holds a bed of lime.
He tied the knots himself. Nobody else had ever been allowed to.
One knot for each course of wall that had stood through a winter. He tied them at the end of the thaw, when the frost had gone out of the joints and the masons could tell whether the lime had taken. A course that had sagged was not knotted. A course that had cracked was not knotted. A course that had stood, every stone seated, every joint dry and grey and sound, was tied with a single turn of the twine and pulled tight, and the knot was left at the height of the course it belonged to, so that a man walking the wall could see, at a glance, how much of the Hold had held.
