For centuries, blacksmiths made nails one at a time, at considerable expense, by drawing a short rod of red-hot iron, hammering one end to a point and pounding the other end to a head.

• 几世纪以来，铁匠都以高昂的成本，锤打出一支支的钉子：先拉长烧红的短铁条，再将一头敲成尖端，另一头锤打成钉头。