What is (a) A movable slab or rubber used in grinding or polishing a surface of stone. (b) A tool on which lenses are fastened in a group, for polishing or grinding called?

runner — (Mech.) (a) A movable slab or rubber used in grinding or polishing a surface of stone. (b) A tool on which lenses are fastened in a group, for polishing or grinding. (Webster's 1913.)

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