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.
When the bearing is properly lubricated this. phenomenon commences as a crack below the surface and propagates to the surface causing a pit or a spall in the bearing raceway. The high level of cleanliness of bearing steels in current bearing technology is one factor in minimizing the probability of fatigue. spalls.