Benjamin Chew Tilghman

Benjamin C. Tilghman of Philadelphia, Pennsylvania was an inventor who patented a method of cutting and engraving stone, metal, glass and other hard materials in 1870. His patent describes cutting, boring, grinding and engraving by driving a stream of sand or quartz grains against the material at high speed. He preferred a jet of steam to drive the sand but allowed a revolving fan or drum, and compared each grain to a small projectile that cuts or indents what it strikes.