The Scottish Whistle
Whistle Tutorial - Lesson 8.3
LOOK AT THE NOTATION in Comin' Thro' the Rye, and Burning of the Piper's Hut; notice that almost half the notes have dots after them. If a note has a dot after it, it increases its length by half. If the first of two quarter notes is replaced by a dotted quarter note, the length of the second note must be decreased to compensate (see fig. 1).
The same goes for any note. If an eighth note is dotted, the next note has to be halved to compensate (in fig. 2 the eighth note becomes a sixteenth note - you can tell it's half the length because it has two tails instead of one.). This is the rhythm of most hornpipes and odd examples of other types of tune.
One characteristic of Scottish music is called the snap, when a short note is followed by a longer note, such as in Strathspeys. What is happening during the snap is that it is the second of two notes that is dotted, and the first note is halved to compensate. For fun, try playing a well known tune, but "Scotticise" it by putting snaps in here and there.
Here is an exercise in irregular rhythms - try to hear the dotted notes longer, and the following notes shorter to compensate. [MIDI file]