The cradle-rockers had done hard duty for so many years, under the weight of so many children, on that flagstone floor, that they were worn nearly flat, in consequence of which a huge jerk accompanied each swing of the cot, flinging the baby from side to side like a weaver's shuttle, as Mrs Durbeyfield, excited by her song, trod the rocker with all the spring that was left in her after a long day's seething in the suds.