| 摘要 |
A ruler structure of the aid is formed with mathematical accuracy from the system of twelve basic keys, i.e. A to G on white notes, plus five 'black note' keys. Its scale components are formed as apertured strips, black on one side, white on the other, with arrows pointing to the right. - The white side is used for scales which commence on a white key, the black side for those commencing on a black key. The structure is placed over the complete keyboard of an instrument, and when the scale components are adjusted, the required scale with its corresp. keys can be viewed. |
