BASON, or Dish, among glass-grinders. These artificers use basons of different materials, as copper, iron, &c. and of various forms, some deeper, others shallower, according to the focus of the glasses that are to be ground. In these basons it is that convex glasses are formed, as concave ones are formed on spheres or bowls. Glasses are worked in basons two ways. In the first, the bason is fitted to the arbor or tree of a lathe, and the glass, fixed with cement to a handle of wood, is presented and held fast in the right hand within the bason, while the proper motion is given by the foot to the bason. In the other, the bason is fixed to a stand or block, and the glass with its wooden handle is moved. The movable basons are very small, seldom exceeding five or six inches in diameter; but the others are larger, sometimes exceeding ten feet diameter. After the glass has been ground in the bason, it is smoothed with grease and emery, then polished with tripoli, and lastly, finished with paper cemented to the bottom of the bason.