These containers are either cylindrical and horizontal or spherical. Examples include spherical and cylindrical symmetry. Wok rings are sold in cylindrical and conical shapes. The stones were normally ground into cylindrical or spherical beads. Eyeglass lenses that combine spherical and cylindrical correction are toric lenses. Is suitable for cylindrical, rectangular or oval bottles. The conical/cylindrical transition piece at frame 67 followed instantly. These are radial (cylindrical), bilateral, biradial and spherical symmetry. Two rectangular, one cylindrical and a cube. See also the differential volume entry in nabla in cylindrical and spherical coordinates. Ideal models such as cylindrical, hexagonal and square models are common. The anode is at one end of a cylindrical tube. This excites the air contained in the usually cylindrical resonant cavity within the flute. His boilers worked at and were at first of hemispherical then cylindrical form. The tube may be cylindrical or oval in shape.