Let the work be set out and first lightly prick-punched; then clamp to place lightly as near as possible, but never set the "dead-centre" against the work, for that will not bring it true; now with a scratch-awl or sharp-pointed centre, with the point resting in the prick-mark, and the other end held against or on the dead centre, revolve the work. If the point marked for the centre of the hole is out of true, the scratch-awl, or whatever rests in the point, will vibrate. Put into the lathe-rest a tool, without fastening it, and push it up to the scratch as the work is revolved, and the extent of the vibration can be seen. The work can be driven as thus indicated when there is no vibration of the scratch or centre, the work is perfectly set, and may be securely fastened.