When C is taken as 1, the scale or Key is said to be in its natural position; but either of the oth­er letters may be laken as 1, in Avhieh case the scale is, said to be Transposed. As 1 is the basis of the scale, the foundation on which it rests, so the letter which is taken for the sound is called the Key-Note. Thus, if the scale be in its natural position, it is said to be in the key of C; if G betaken as 1, the scale is in the key of G; if D be taken as 1, the scale is in the key of D, and so on -with the rest of the,seven letters; whichever letter is taken as 1, that letter be­comes the key-note of the scale.
In transposing the scale, the order of the intervals, or tones and semitones, must be pre­served. Thus, the interval must always be a tone from i to 2, a tone 2*to 3, a semitone from 3 to 4, a tone from 4 to 5, a tone from 5 to"6, a tone from 6 to 7, and a semitone from 7 to 8. The interval from one letter to another letter is also the same and cannot be changed,— thus it is always a tone from C to D, and from D to E, a semitone from E to F; a tone from F to G, from G to A, from A to B; and a semitone from B to C. In the transposition of the scale, therefore, it becomes necessary to introduce sharps and flats,or to substitute sharrpened or flattened letters, so as to preserve the proper order of the intervals.
First transposition by sharps from C to G, a fifth higher, or a fourth lower.

The same method is followed in all the transpositions by sharps, viz- the fifth above or fourth below is taken as 1 of a new key, in every succeeding: transposition, and an additional sharp will be required also in every succeeding transposition.
To transpose the scale by flats, we take the fourth (instead of the fifth) of every new scale. F is the fourth of C, hence it is 1 of the new scale (key of F). The order of intervals must bo the same in the flat keys as in the sharp; hence the B must be made flat.
Transposition by Flats from C to F, a fourth higher or a fifth lower.



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