Hyemale, commonly known as the Dutch rush, is much more abundant in Holland than in Britain; it is used for polishing purposes.
Amongst the earliest mechanical contrivances of Fraunhofer was a machine for polishing mathematically uniform spherical surfaces.
The industries comprise the manufacture of chemicals and artificial manures, granite polishing, flour and sawmills, bootand shoe-making, carriagebuilding and woollen manufactures.
In the town are' a number of marble-polishing works.
Thus workers in lead suffer from the effects of this substance as a poison, those who work in phosphorus are liable to necrosis of bone and fatty degeneration of the blood vessels and organs, and the many occupations in which dust is inhaled (coalmining, stone-dressing, steel-polishing, &c.; fig.