 A handloom weaver could propel the shuttle by throwing it from side to side with the aid of a picking stick.The "picking" on a power loom is done by rapidly hitting the shuttle from each side using an overpick or underpick mechanism controlled by cams 80–250 times a minute.When a pirn is depleted, it is ejected from the shuttle and replaced with the next pirn held in a battery attached to the loom.