In using a pair of watchmakers' turns when putting a new cylinder in a watch, the cylinder must have a brass ferrule affixed to it by shellac. It is rotated by means of a light whalebone bow about 9 in. long, strung with a horsehair. The motion given by a bow is backward and forward, therefore cutting is only done on the forward or down stroke, the graver being held slightly away from contact with the work during the up stroke - that is, the backward motion of the bow.