III
THE MAJOR SCALES
We have developed additional material for the teaching of the scales. Here we show a chart somewhat suggesting the arrangement of the bell material used in the first exercises. That is, the relative intervals between the various notes of the scale are clearly indicated. The scale is, in fact, a series of eight sounds, the intervals between each being as indicated by the black marks in the design: whole tone, whole tone, semi-tone, whole tone, whole tone, whole tone, semi-tone.
In the do major scale the intervals are indicated as follows: a whole tone between do and re; re and mi; fa and sol; sol and la; la and si; and a semi-tone between mi and fa and si and do. If, however, instead of beginning with do, the scale starts from some other note, the mutual intervals characterizing the scale remain unchanged. It is as though the whole scale with its characteristic construction as regards tone differences were moved along. Accordingly, as our plate shows, under the figure of the two octaves there is another figure. This latter is a movable piece of cardboard which shows the construction of the octave in black and white. This movable card is fastened to the large chart by a ribbon. Supposing now we slide this movable piece, as indicated in the figure, to the level of mi. The intervals between the tones of the mi scale are the same as in all the other scales. In other words, they remain as indicated on the small movable card. It is necessary, accordingly, to strike on the grand scale the notes corresponding to the white spaces of the movable slip: viz.,
mi, fa diesis, sol diesis, la, si, do diesis, re diesis.
This process may be repeated by sliding the movable card to all the notes in succession. In this way all the scales are gradually constructed. This becomes an interesting theoretical exercise, since the child discovers that he is able to build all possible scales by himself.
The monocord. In the first instrument the notes are indicated by frets. On the monocord in the foreground the child places the frets as he discovers the notes by drawing the bow across the string.
Material for indicating the intervals of the major scale and its transposition from one key to another.