Sand Blast, one of the most wonderful uses of sand, by means of which glass, stone, metals, or any other hard substance may be cut or engraved. If a stream of sharp sand be let fall from a high box (as high as the ceiling of a room) through a tube on to a plate of glass held under it, the sand will cut away little grains of the glass till at length the whole surface will be cut or scratched and it will look like ground glass. If, instead of cutting the glass all over, it is wanted to engrave a pattern or figure all over, the workman only has to cover the parts of the glass which he does not want cut with a stencil plate made with leather, rubber, paper, wax, etc., for the sand will not cut any soft surface. Metals and stones may also be cut by means of the sand blast, which will not only scratch the surface, but will cut it away to any depth. The marble tombstones put up in the National cemeteries to the memories of soldiers killed in the war were made in this way. Iron letters were fastened on to the smooth face of the stone, which was then put under the sand blast, and the sand cut away all the marble not covered by the letters. when the iron patterns were taken off, the letters were left raised as if they had been cut out with the chisel. The work was done so fast that 300 headstones were made in a day, or as many as 300 men could have done in the same time, working with the hammer and chisel.
Entry from Everybody's Cyclopedia, 1912.