a special-purpose lathe, the rose engine lathe, is also used for ornamental turning, in particular for engine turning, typically in precious metals, for example to decorate pocket-watch cases. as well as a wide range of accessories, these lathes usually have complex dividing arrangements to allow the exact rotation of the mandrel. cutting is usually carried out by rotating cutters, rather than directly by the rotation of the work itself. because of the difficulty of polishing such work, the materials turned, such as wood or ivory, are usually quite soft, and the cutter has to be exceptionally sharp. the finest ornamental lathes are generally considered to be those made by holtzapffel around the turn of the 19th century.