Scale for the Blind 1996 Wood, masonite, graphite, felt, enamel, with diagram. disk: 12 x 12 x 0.5 Facsimile disk for 19th century 'whirling table' used to demonstrate the vibration ratios of musical harmonies. The disk was placed on the machine and rotated with a uniform speed. Beginning with the inner circle of holes, a stream of air was blown against each row of holes in succession to produce the tones recognized as: do, mi, sol, do, forming a major chord.