The folk-tunes of America are not, in the main, built up on scales of
the diatonic major and minor systems which, as is well known, have
assumed their present form under the demands of _harmony_; but on a
modal system which grew out of _melodic_ exigences long before harmony
made its conquest of the music of western civilisation. Nor do the
folk-tunes of this country make use of all the tones of even these
modal scales. They often employ but five or six of the seven available
tones, leaving characteristic gaps in such scales.
American folk-tune collectors have had their troubles in the
interpretation of modal melodies. I have had mine. Even such a
life-long student of these things as Cecil Sharp met many a knotty
problem in classifying his Appalachian tunes. In view of this
difficulty I called on Hilton Rufty, a thorough musician and a
reliable authority in the folk-music field, to lend a hand in the
modal classification of these tunes. He generously acceded to my
request; and by the time my requests had ceased and before his
generosity had been exhausted he had checked or corrected all my modal
classifications of the tunes in this collection. In making clear Mr.
Rufty's effective and practical method of identifying the character of
tunes I shall reproduce his Classification Chart and quote here his
explanation of it.