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.
The spindle is usually the strongest part and is supported by large bearings. Whether the spindle holds the work or the tool, an automatic clamping feature allows the spindle to rapidly clamp and unclamp during the program run. Cast iron or Meehanite used to be the material of choice for metal-working machines.