Text: To determine the number name of an interval we must be able to count from one to nine, and to say the first seven letters of the alphabet. To determine the specific name of an interval we must know the Major Scale of the lower tone of the given interval. This will inform us if the upper tone of the given intereval be in the Major Scale of the lower tone, or if it be above the Major Scale tone, or if it be below it. RULE: An interval is Major when the upper tone is found in the Major Scale of the lower tone. D (in the diagram) is the sixth degree or step or tone in the Major Scale of F. Numerically F to D is a Sixth. Hence the interval is accurately described when we say it is a Major Sixth. Major Intervals are the 2nd, 3rd, 6th, 7th and 9th.

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