Sphere
A solid contained under one uniform round surface, such as would be formed by revolving a circle about a diameter thereof as an axis. Every point on the surface of a sphere is equally distant from its centre. Spider, or tripod, is an end attachment for a core-barrel, to be used when the core must be suspended within the mould by means of bearings at the top--as in guns and hydraulic cylinders. It consists of a central vertical bush, with three arms extending horizontally, on the ends of which are vertical standards which constitute as many legs or feet, which must rest on the outer mould or cope. The central bush encircles the barrel, and is connected with the latter by means of three lugs, which are cast on the barrel, the holes in which correspond to three other holes in the spider. See ORNANCE.