and 29 of each of the polishing wheels 30 a and 30 b respectively are positioned parallel to the major surface 16 of the glass sheet 10 in the embodiment shown in fig1 the grinding wheels 20 a and 20 b each rotate in opposite directions specifically grinding wheel 20 a rotates in a counterclockwise direction whereas grinding wheel 20 b rotates in a clockwise direction similarly polishing wheels 30 a and 30 b each rotate in opposite directions specifically polishing wheel 30 a rotates in a counterclockwise direction whereas polishing wheel 30 b rotates in a clockwise direction as shown in fig1 the grinding surface 21 of the grinding wheel 20 b contacts one of the edges 14 of the glass sheet 10 whereas the grinding surface 22 of the grinding wheel 20 a contacts an opposite edge 12 of the glass sheet 10 similarly the polishing surface 32 of the polishing wheel 30 a contacts the edge 12 of glass sheet 10 whereas the polishing surface 31 of the polishing wheel 30 b contacts the edge 14 of the glass sheet 10 in the preferred embodiment each of the grinding wheels 20 a and 20 b and each of the polishing wheels 30 a and 30 b rotate simultaneously moreover.