It is interesting further to note that the upper tetrachord of any sharp scale is always used without change as the lower tetrachord of the next major scale involving sharps, while the lower tetrachord of any flat scale is used as the upper tetrachord of the next flat scale. See Figs. 54 and 55.
83. From the standpoint of staff notation the major scale may be written in fifteen different positions, as follows:
It will be observed that in the above series of scales those beginning on F♯ and G♭ call for the same keys on the piano, i.e., while the notation is different, the actual tones of the scale are the same. The scales of C♯ and D♭ likewise employ the same tones. When two scales thus employ the same tones but differ in notation they are said to be enharmonic, (cf. [p. 38], [Sec. 93].)