GRINDSTONE. - Grit Stones or Grinding Stones are varieties of sandstones, some of which are described. 1. - "Newcastle Grindstones abound in the coal districts of Northumberland, Durham, Yorkshire and Derbyshire; and are selected of different degrees of density and coarseness, best suited to the various manufactures of Sheffield and Birmingham, for grinding and giving a smooth and polished surface to their different wares." 2. - "Bilston Grindstone is a similar description of stone, of great excellence, it is of a lighter colour, much finer and of a very sharp nature, and at the same time not too hard. It is confined to a very small spot of limited extent and thickness, in the immediate vicinity of Bilston, in Staffordshire, where it lies above the coal, and is now quarried entirely for the purpose of grindstones." 3. - "Carpenters' Rubstone is a hard close variety, used as a portable stone for sharpening tools by rubbing them on the flat stone instead of grinding. It is also much employed for the purpose of giving a smooth and uniform surface to copper plates for the engraver."

A much softer variety of sandstone, is usually cut into a square form from eight to twelve inches long, in which state they are used dry by shoe-makers, pocket-book makers, cork-cutters, and others, for giving a sort of rough edge to their bladed knives and instruments of a similar description.

4. - "Devonshire Batts. - A porous fine-grained sandstone in considerable repute, from the quarries of Black Down Cliffs, near Collumpton." 5. - "Yorkshire Grit is a variety not at all applied as a whetstone, but is in considerable use as a polisher of marble, and of copper plates for engravers." 6. - "Congleton Grit is a very similar stone of a softer nature, and made use of by the same description of workmen." 7. - Sheffield Grindstone is a hard coarse grit stone used for grinding large files, and similar purposes, it is obtained from Hardsley which lies about 14 miles north of Sheffield. 8. - Wickersley Grindstones are very generally used in Sheffield for most purposes of grinding, as knives, scissors, razors, saws, and edge tools generally. Wickersley stones are quarried at a village of that name about 9 miles east of the town of Sheffield. 9. - Sheffield BluestoneIs a finer grained stone than either of the last two kinds, and is very generally used at Sheffield for finishing the grinding of articles of cutlery, that have been prepared on the Wickersley stones. The act of grinding on a blue stone is called "whittening" and the blades of table and pocket knives are always'thus treated in Sheffield. The bluestones are found very abundantly in the neighbourhood of Sheffield at from 1/2 to 1 1/2 miles on the north and south sides of the town.