Athenian cultural dominance continued throughout the Roman period, and the buildings added to the Agora reflect the educational role of the city, a role that ended only with the closing of the pagan philosophical schools by the Christian emperor Justinian in A.D. 529.
Bearing, in machine construction, a connector (usually a support) that permits the connected members to rotate or to move in a straight line relative to one another. Often one of the members is fixed, and the bearing acts as a support for the moving member. Most bearings support rotating shafts against either transverse (radial) or thrust (axial) loads.
bit1. 1  Machinery. a removable drilling or boring tool for use in a brace, drill press, or the like. a removable boring head used on certain kinds of drills, as a rock drill. a device for drilling oil wells or the like, consisting of a horizontally rotating blade or an assembly of rotating toothed wheels.